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Inheritance

1

Autosomal dominant inheritance of glomuvenous malformation HP:0000006

Familial multiple glomangioma (glomuvenous malformation) segregates as an autosomal dominant trait caused by GLMN loss-of-function variants, with incomplete penetrance and variable expressivity attributed to the requirement for a somatic second hit (paradominant inheritance).

Autosomal dominant inheritance

Show evidence (1 reference)

PMID:23375657 SUPPORT Human Clinical

"Inherited vascular malformations are commonly autosomal dominantly inherited with high, but incomplete, penetrance; they often present as multiple lesions."

Describes the autosomal dominant, incompletely penetrant, multifocal inheritance pattern of glomuvenous malformation.

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Subtypes

8

Solid Glomus Tumor

The most common histologic variant, characterized by nests and sheets of uniform glomus cells with relatively inconspicuous vasculature. Typically solitary, subungual, and painful.

Show evidence (1 reference)

PMID:27184662 SUPPORT Human Clinical

"We assessed 9 cases of solid glomus tumors (SGT), 8 cases of glomus tumors with vascular ectasia (VEGT), 2 cases of glomangiomyomas (GMM) and 6 cases of glomuvenous malformation (GM)."

An immunohistochemical series that enumerates the recognized histologic variants of glomus tumor, including this one.

Glomangioma (Glomuvenous Variant)

A variant dominated by dilated, cavernous venous-like vascular channels rimmed by only a few layers of glomus cells. Glomangiomas account for the great majority of multiple and familial lesions.

Show evidence (1 reference)

PMID:27184662 SUPPORT Human Clinical

"We assessed 9 cases of solid glomus tumors (SGT), 8 cases of glomus tumors with vascular ectasia (VEGT), 2 cases of glomangiomyomas (GMM) and 6 cases of glomuvenous malformation (GM)."

An immunohistochemical series that enumerates the recognized histologic variants of glomus tumor, including this one.

Glomangiomyoma

The least common variant, in which glomus cells show transition to elongated, frankly mature smooth muscle cells around the vascular channels.

Show evidence (1 reference)

PMID:27184662 SUPPORT Human Clinical

"We assessed 9 cases of solid glomus tumors (SGT), 8 cases of glomus tumors with vascular ectasia (VEGT), 2 cases of glomangiomyomas (GMM) and 6 cases of glomuvenous malformation (GM)."

An immunohistochemical series that enumerates the recognized histologic variants of glomus tumor, including this one.

Glomuvenous Malformation (Familial Multiple Glomangioma)

An inherited, multifocal cutaneous vascular malformation caused by loss-of-function variants in GLMN (glomulin). Lesions are typically multiple, blue-purple, compressible plaques or nodules that are less painful than solitary solid glomus tumors, and they are inherited in an autosomal dominant pattern with incomplete penetrance explained by a paradominant somatic second hit.

Show evidence (1 reference)

PMID:15689436 SUPPORT Human Clinical

"Glomuvenous malformation (GVM) ("familial glomangioma") is a localised cutaneous vascular lesion histologically characterised by abnormal smooth muscle-like "glomus cells" in the walls of distended endothelium lined channels."

Defines glomuvenous malformation as the inherited, glomus-cell-lined vascular lesion subtype.

Glomangiomatosis

A rare variant in the Folpe classification showing the histologic features of diffuse angiomatosis together with an excess of glomus cells. Despite its infiltrative, angiomatosis-like growth it behaves benignly: no case in the defining series metastasized.

Show evidence (1 reference)

PMID:11145243 SUPPORT Human Clinical

"Glomangiomatosis: Tumors with histologic features of diffuse angiomatosis and excess glomus cells."

States the Folpe definition of glomangiomatosis as a distinct category in the glomus tumor classification scheme.

Symplastic Glomus Tumor

A tumor showing high nuclear grade (marked nuclear atypia/pleomorphism) in the absence of any other malignant feature. This is explicitly NOT a malignant glomus tumor: in the defining series, high nuclear grade alone was not associated with metastasis, and no symplastic tumor metastasized. The atypia is regarded as degenerative rather than as evidence of malignancy.

Show evidence (2 references)

PMID:11145243 SUPPORT Human Clinical

"Symplastic glomus tumor: Tumors with high nuclear grade in the absence of any other malignant feature."

States the Folpe definition of the symplastic category.

PMID:11145243 SUPPORT Human Clinical

"metastatic disease was not seen in any specimen classified as symplastic glomus tumor, glomus tumor of uncertain malignant potential, or glomangiomatosis."

Establishes that the symplastic category is prognostically benign, which is why it must not be collapsed into malignant glomus tumor.

Glomus Tumor of Uncertain Malignant Potential

The Folpe intermediate category: tumors that lack the criteria for malignant glomus tumor or symplastic glomus tumor but have high mitotic activity with superficial location only, or large size only, or deep location only. That is, exactly one worrisome feature is present rather than the qualifying combination. No tumor in this category metastasized in the defining series.

Show evidence (2 references)

PMID:11145243 SUPPORT Human Clinical

"Glomus tumor of uncertain malignant potential: Tumors that lack criteria for malignant glomus tumor or symplastic glomus tumor but have high mitotic activity and superficial location only, or large size only, or deep location only."

States the Folpe definition of the uncertain-malignant-potential category and its exact feature combination.

PMID:32604167 SUPPORT Human Clinical

"Seventy-two cases were benign, 17 cases were malignant and 4 were of uncertain malignant potential."

Independently confirms that the uncertain-malignant-potential category is applied in contemporary molecular-pathology cohorts, at roughly 4% of tumors.

Malignant Glomus Tumor (Glomangiosarcoma)

A rare aggressive form defined by deep location together with size greater than 2 cm, the presence of atypical mitotic figures, or moderate-to-high nuclear grade with at least 5 mitotic figures per 50 high-power fields. Capable of local recurrence and distant metastasis. Note that the three qualifying criteria are alternatives, and that high nuclear grade alone (symplastic glomus tumor) or a single worrisome feature alone (uncertain malignant potential) does NOT meet this definition.

Show evidence (2 references)

PMID:11145243 SUPPORT Human Clinical

"Malignant glomus tumor: Tumors with a deep location and a size of more than 2 cm, or atypical mitotic figures"

States the consensus morphologic criteria that define the malignant glomus tumor subtype.

PMID:11145243 SUPPORT Human Clinical

"High nuclear grade alone, infiltrative growth, and vascular space involvement were not associated with metastasis."

Bounds the malignancy definition: the features that do NOT by themselves qualify a tumor as malignant, which is why symplastic tumors are a separate category.

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Discussions and Knowledge Gaps

3

What drives the classic painful subungual glomus tumor, given that this commonest subset lacks the MIR143-NOTCH fusions that define the disease molecularly?

KNOWLEDGE GAP OPEN glomus-subungual-fusion-negative

Attached to

pathophysiology#MIR143-NOTCH Gene Fusion

The molecular model of glomus tumor rests on MIR143-NOTCH fusions found in over half of tumors, but the same cohort reports that the common subungual subset - the lesions that produce the classic clinical triad and account for most clinical practice - is fusion-negative. The BRAF/KRAS and NF1 arms do not fill the gap either: sporadic tumors showed no NF1 or RAS-MAPK abnormality, and BRAF V600E is enriched in proximal rather than distal lesions. The entry therefore models a driver landscape that does not explain its own flagship phenotype. Until this is resolved, no causal edge should be drawn from the fusion node to the subungual presentation.

Proposed experiments

RNA sequencing of fusion-negative subungual glomus tumors

exp_glomus_subungual_fusion_negative_rnaseq

Sequence a dedicated cohort of classic painful subungual glomus tumors confirmed NOTCH-fusion-negative by break-apart FISH, to search for alternative fusions, cryptic NOTCH-pathway lesions, or an entirely distinct driver class.

Site-stratified methylation and single-cell profiling

exp_glomus_site_stratified_profiling

Compare subungual with deep and visceral glomus tumors by DNA methylation classification and single-cell profiling, to test whether they are one entity reached by two driver routes or two entities that converge on a shared morphology.

Show evidence (2 references)

PMID:32604167 SUPPORT Human Clinical

"The common subungual GT subset lack NOTCH-gene fusions suggesting an alternative pathogenesis."

States the gap directly: the commonest clinical subset is not explained by the defining molecular driver.

PMID:19738042 SUPPORT Human Clinical

"No abnormalities in NF1 or RAS mitogen-activated protein kinase activation were found in sporadic glomus tumors."

Excludes the NF1/RAS-MAPK route as the alternative driver in sporadic tumors, narrowing the gap.

What is the population incidence of glomus tumor, and is the reported sex predominance real or an artifact of which anatomic subset a series samples?

KNOWLEDGE GAP OPEN glomus-epidemiology-gap

No population-based rate exists, so the prevalence record on this entry carries only the qualitative RARE band. The sex data are also internally inconsistent across the cited series in a way that looks anatomic rather than biological: a hand-only series reports 71% female, whereas a molecular-pathology cohort dominated by deep, visceral and NOTCH-rearranged tumors reports 82% male among benign fusion-positive cases. These may be two different populations rather than a contradiction, but the entry does not assert a sex ratio because the evidence cannot currently distinguish those possibilities.

Proposed experiments

Registry-based incidence estimation

exp_glomus_registry_incidence

Estimate glomus tumor incidence from a population cancer or national pathology registry (e.g. SEER), stratified by acral versus deep/visceral site, to replace the current qualitative RARE band with a rate.

Site-stratified pooled analysis of sex ratio

exp_glomus_pooled_sex_ratio

Pool published glomus tumor series with site stratification to test whether the apparent contradiction between female-predominant hand series and male-predominant deep/visceral molecular cohorts is explained by anatomic sampling.

Show evidence (2 references)

PMID:34239958 SUPPORT Human Clinical

"Out of 17 patients, majority (n=12; 70.58%) were females."

The female-predominant hand series.

PMID:32604167 SUPPORT Human Clinical

"Among the 34 cases of benign NOTCH-rearranged GT, most occurred in males (n=28, 82%)"

The male-predominant molecular cohort, drawn from a different anatomic distribution.

Where should the ICD-O morphology codes 8711/0 (glomus tumour, benign) and 8711/3 (glomangiosarcoma) be recorded?

CURATION TODO OPEN glomus-icdo-morphology-unrepresentable

MONDO:0018327 carries the xref ICDO:8711/0, but neither the coarse ICDOMorphologyEnum used by classifications.icdo_morphology (whose ten values are Carcinoma, Adenocarcinoma, Squamous Cell Carcinoma, Sarcoma, Leukemia, Lymphoma, Multiple Myeloma, Melanoma, Glioma, Embryonal Neoplasm) nor DiseaseMappings (icd10cm/icd11f/mondo/ncit only) can hold a four-digit ICD-O morphology code. Assigning "Sarcoma" would be wrong, since the great majority of glomus tumours are benign. The classifications block is therefore deliberately omitted from this entry rather than populated incorrectly. Resolving this needs a schema change, not a curation change.

Escalated to a schema issue as monarch-initiative/dismech#7548 (assigned to @cmungall) during review of PR #7484. When that issue is resolved, populate this entry with ICD-O 8711/0 for the benign entity and 8711/3 for the malignant glomus tumour subtype, then close this discussion.

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Pathophysiology

8

MIR143-NOTCH Gene Fusion

Recurrent somatic rearrangements juxtapose the MIR143 locus in band 5q32 to a NOTCH gene family member. NOTCH2 (1p13) is by far the most frequent partner, with NOTCH1 (9q34) and NOTCH3 also reported. The rearrangement places a truncated NOTCH segment under control of the highly expressed MIR143 locus, producing marked overexpression of a ligand-independent NOTCH product in the perivascular myoid tumor cell. NOTCH2 and NOTCH3 are the physiologic regulators of vascular smooth muscle development, which is consistent with a perivascular myoid lineage for the resulting neoplasm. Importantly, the common subungual glomus tumor subset is largely fusion-negative, indicating that an alternative, still-undefined pathogenesis operates at that site.

glomus cell (modified perivascular smooth muscle cell) CL:0000192

NOTCH2 hgnc:7882 NOTCH3 hgnc:7883 NOTCH1 hgnc:7881 MIR143 hgnc:31530

Notch signaling pathway GO:0007219 ⚠ ABNORMAL

Downstream

Glomus Cell Proliferation Around Distorted Vascular Channels Deregulated NOTCH signaling in perivascular myoid cells drives clonal expansion of the modified smooth muscle cells of the glomus body.

Show evidence (4 references)

PMID:23999936 SUPPORT Human Clinical

"A gene fusion involving MIR143 in band 5q32 was identified in both GTs with either NOTCH2 in 1p13 in GT1 or NOTCH1 in 9q34 in GT2"

Landmark RNA-sequencing study identifying the MIR143-NOTCH fusion as the recurrent driver rearrangement of glomus tumor.

PMID:23999936 SUPPORT Human Clinical

"Overall NOTCH2 gene rearrangements were identified in 52% of GT, including all malignant cases"

Quantifies NOTCH2 rearrangement prevalence and its presence in all malignant tumors of the series.

PMID:32604167 SUPPORT Human Clinical

"rearrangements of NOTCH genes are seen in over half of GT, with NOTCH2-MIR143 being the most common fusion (73%)"

Confirms in a 93-tumor cohort that NOTCH fusions occur in the majority of glomus tumors, with NOTCH2-MIR143 predominating.

+ 1 more reference

Constitutive Mitogenic Pathway Activation

A separate, largely fusion-independent subset of glomus tumors carries activating lesions of the RAS-MAPK axis. Inactivating NF1 mutations remove RAS-GAP restraint and produce constitutive RAS/MAPK signaling; activating BRAF p.Val600Glu signals independently of upstream RAS; and KRAS mutations occur predominantly in distal tumors while BRAF V600E is enriched in proximal ones. All converge on sustained MEK-ERK output, providing an alternative mitogenic drive to glomus cell proliferation and a rationale for BRAF and MEK inhibition in advanced disease.

glomus cell (modified perivascular smooth muscle cell) CL:0000192

BRAF hgnc:1097 KRAS hgnc:6407 NF1 hgnc:7765

MAPK cascade GO:0000165 ↑ INCREASED

Downstream

Glomus Cell Proliferation Around Distorted Vascular Channels Sustained MEK-ERK output provides a fusion-independent proliferative drive in RAS-MAPK-altered glomus tumors.

Show evidence (4 references)

PMID:41693210 SUPPORT Human Clinical

"Key discoveries include frequent inactivating mutations in the NF1 gene, leading to constitutive RAS/MAPK pathway activation, and recurrent "MIR143-NOTCH" gene fusions disrupting Notch signaling"

Establishes constitutive RAS/MAPK activation, alongside NOTCH fusion, as a recurrent oncogenic driver mechanism in glomus tumor.

PMID:32604167 SUPPORT Human Clinical

"half of the GT showing NOTCH-gene fusions and a smaller subset BRAF V600E mutations"

Documents BRAF V600E as the alternative driver in a smaller subset of glomus tumors.

PMID:40976119 SUPPORT Human Clinical

"Pathway enrichment analysis revealed KRAS mutations were predominant in distal GT, while BRAF V600E mutations were more prevalent in proximal locations."

Next-generation sequencing of 44 tumors shows anatomically stratified RAS-MAPK pathway lesions in glomus tumor.

+ 1 more reference

NF1 Biallelic Inactivation

Individuals with neurofibromatosis type 1 carry a germline inactivating NF1 variant and are predisposed to digital glomus tumors. Lesion formation requires somatic loss of the remaining wild-type allele; in a substantial minority this second hit is copy-neutral loss of heterozygosity produced by mitotic recombination of chromosome arm 17q rather than an intragenic mutation. Loss of neurofibromin, the RAS GTPase-activating protein encoded by NF1, removes the brake on RAS and produces RAS-MAPK hyperactivation in the glomus cell. Sporadic glomus tumors show no NF1 or RAS-MAPK abnormality, so this is a distinct, syndromic route into the same downstream mitogenic node.

glomus cell (modified perivascular smooth muscle cell) CL:0000192

NF1 hgnc:7765

negative regulation of Ras protein signal transduction GO:0046580 ↓ DECREASED Ras protein signal transduction GO:0007265 ↑ INCREASED

Downstream

Constitutive Mitogenic Pathway Activation Loss of neurofibromin GAP activity releases RAS, feeding the shared constitutive RAS-MAPK node.

Show evidence (3 references)

PMID:19738042 SUPPORT Human Clinical

"Genetic analysis showed germ line and somatic NF1 mutations in seven tumors."

Demonstrates the two-hit germline-plus-somatic NF1 genotype in NF1-associated glomus tumors.

PMID:19738042 SUPPORT In Vitro

"RAS mitogen-activated protein kinase hyperactivation was observed in cultured NF1(-/-) glomus cells, reflecting a lack of inhibition of the pathway by functional neurofibromin, the protein product of NF1."

Functional evidence in cultured NF1-null glomus cells linking neurofibromin loss directly to RAS-MAPK hyperactivation.

PMID:22250039 SUPPORT Human Clinical

"We have observed mitotic recombination in 22% of molecularly characterized NF1-associated glomus tumors"

Identifies mitotic recombination of 17q as a recurrent mechanism for the somatic second hit that reduces the germline NF1 variant to homozygosity.

GLMN Loss of Function with Somatic Second Hit

Germline truncating variants in GLMN (glomulin) cause the inherited multiple form, glomuvenous malformation. Inheritance is autosomal dominant with incomplete penetrance and focal lesions, explained by a paradominant (Knudson two-hit) mechanism in which a somatic second hit inactivates the remaining wild-type allele locally; in most lesions this second hit is acquired uniparental isodisomy of chromosome 1p rather than an intragenic mutation. Glomulin normally binds the RING domain of Rbx1 and inhibits its E3 ubiquitin ligase activity, stabilizing the substrate receptor Fbw7; its loss accelerates Fbw7 turnover and raises Cyclin E and c-Myc levels, releasing a proliferative brake in the vascular wall and leaving the smooth muscle compartment arrested in an incompletely differentiated, glomus-like state around distended venous channels.

vascular smooth muscle cell CL:0000192

GLMN hgnc:14373

protein ubiquitination GO:0016567 ↑ INCREASED

Downstream

Glomus Cell Proliferation Around Distorted Vascular Channels Biallelic glomulin inactivation blocks terminal vascular smooth muscle differentiation and de-represses Cyclin E/c-Myc, yielding multifocal glomus-cell-lined venous channels.

Venous Malformation Loss of glomulin produces the distended, poorly muscularized venous channels that give glomuvenous malformations their compressible, blue-purple appearance.

Show evidence (3 references)

PMID:23375657 SUPPORT Human Clinical

"Occurrences of these mutations render the inherited glomulin variant in 1p22.1 homozygous in the affected tissues without loss of genetic material. This finding demonstrates that a double hit is needed to trigger formation of a GVM."

Direct demonstration of the somatic second hit (acquired uniparental isodisomy) required for lesion formation in glomuvenous malformation.

PMID:15689436 SUPPORT Human Clinical

"This finding suggests that GVM results from complete localised loss of function and explains the paradominant mode of inheritance."

Establishes complete local loss of glomulin function as the mechanism and names the paradominant inheritance model.

PMID:22405651 SUPPORT In Vitro

"Loss of Glmn in a variety of cells, tissues, and GVM lesions results in decreased levels of Fbw7 and increased levels of Cyclin E and c-Myc."

Provides the molecular consequence of glomulin loss, linking it to stabilization of the proliferative effectors Cyclin E and c-Myc.

Glomus Cell Proliferation Around Distorted Vascular Channels

Whichever driver lesion is present, the tumor is formed by clonal expansion of glomus cells, the modified perivascular smooth muscle cells of the thermoregulatory glomus body. Immunohistochemical expression of smoothelin confirms that these cells are genuinely contractile smooth muscle cells. The proliferating cells form solid nests and concentric cuffs around branching, ectatic vascular spaces, replacing the normal Sucquet-Hoyer canal architecture of the arteriovenous anastomosis, and deposit a continuous pericellular type IV collagen basement membrane that reflects their retained myoid phenotype.

glomus cell (modified perivascular smooth muscle cell) CL:0000192 pericyte CL:0000669

smooth muscle cell proliferation GO:0048659 ↑ INCREASED extracellular matrix organization GO:0030198

Downstream

Nociceptor-Rich and Mast-Cell-Rich Tumor Stroma The expanding glomus tumor is densely invested by unmyelinated sensory nerve fibers and by stromal mast cells.

Loss of Thermoregulatory Shunt Function Replacement of the normal Sucquet-Hoyer canal disrupts the thermoregulatory arteriovenous shunt formed by the glomus body.

Malignant Transformation A small minority of glomus tumors acquire deep location, large size, atypical mitoses, and nuclear atypia, defining malignant glomus tumor.

Subungual Nodule The expanding cellular mass presents as a small, often bluish subungual or dermal nodule.

Gastric (Visceral) Glomus Tumor The same proliferating glomus cell population arising in the gastric wall rather than at an acral site presents as a submucosal antral mass. Because the visceral lesion is histologically and immunophenotypically the same entity as the soft tissue one, this node is its proximate cause too; only the anatomic site, and therefore the clinical presentation, differs.

Show evidence (2 references)

PMID:41693210 SUPPORT Human Clinical

"Glomus tumor (GT) is a rare mesenchymal neoplasm presumed to originate from the neuromyoarterial glomus body."

Establishes the neuromyoarterial glomus body as the cell of origin for the proliferating tumor population.

PMID:27184662 SUPPORT Human Clinical

"Smoothelin expression in glomic cells indicates that they are contractile smooth muscle cells"

Immunohistochemical confirmation that the proliferating glomus cells are contractile smooth muscle cells, the basis of their myoid phenotype.

Nociceptor-Rich and Mast-Cell-Rich Tumor Stroma

Glomus tumors are unusually densely innervated: numerous unmyelinated nociceptive nerve fibers ramify among the tumor cells, and the stroma contains abundant mast cells that show ultrastructural evidence of degranulation in close apposition to those fibers. Release of histamine and other algogenic granule contents onto adjacent nociceptors, together with pressure transmitted by contraction of the smooth-muscle-like tumor cells within a confined subungual compartment, accounts for the disproportionate severity of pain relative to lesion size.

mast cell CL:0000097

sensory perception of pain GO:0019233 ↑ INCREASED mast cell degranulation GO:0043303 ↑ INCREASED

Downstream

Severe Paroxysmal Pain Activation of the dense intratumoral nociceptor population produces lancinating, paroxysmal pain out of proportion to lesion size.

Pinpoint Tenderness Focal mechanical stimulation of the innervated nodule reproduces the pain, the basis of the Love pin test.

Show evidence (2 references)

PMID:93364 SUPPORT Human Clinical

"Electron microscopy revealed various types and degrees of degranulation of mast cell granules, and also disclosed a close correlation between mast cells and non-myelinated nerve fibers."

Ultrastructural demonstration of degranulating mast cells apposed to unmyelinated nerve fibers within the glomus tumor stroma.

PMID:93364 SUPPORT Human Clinical

"These findings suggest that mast cells may play an algogenic role in solitary glomus tumors"

Proposes mast cell mediator release as the algogenic mechanism underlying glomus tumor pain.

Loss of Thermoregulatory Shunt Function

The normal glomus body is an arteriovenous anastomosis in the dermis whose smooth muscle tone shunts blood away from the capillary bed during cold exposure. Tumor-induced distortion of this structure, combined with cold-evoked contraction of the tumor's smooth-muscle-like cells and sensitization of the surrounding nociceptors, converts a normally innocuous cold stimulus into a painful one.

temperature homeostasis GO:0001659 ⚠ ABNORMAL

Downstream

Cold Hypersensitivity Cold exposure of the affected digit provokes intense pain, the second element of the classic glomus tumor triad.

Show evidence (2 references)

PMID:39392364 SUPPORT Human Clinical

"Glomus tumors (GT) are very rare mesenchymal neoplasms arising from glomus bodies, arteriovenous structures located in the dermis and involved in thermoregulation."

Establishes the thermoregulatory arteriovenous glomus body as the structure from which the tumor arises and whose function it disrupts.

PMID:19738042 SUPPORT Human Clinical

"Glomus tumors are small, benign but painful tumors that originate from the glomus body, a thermoregulatory shunt concentrated in the fingers and toes."

Independently identifies the glomus body as a thermoregulatory shunt concentrated at the digits, linking tumor site to the disrupted function.

Malignant Transformation

Malignant glomus tumor (glomangiosarcoma) is rare and is defined morphologically rather than molecularly: deep anatomic location together with size greater than 2 cm, the presence of atypical mitotic figures, or moderate-to-high nuclear grade with at least 5 mitotic figures per 50 high-power fields. Deep location, size above 2 cm, and atypical mitoses are each independently associated with metastatic risk, whereas high nuclear grade alone (symplastic glomus tumor) is not.

cell population proliferation GO:0008283 ↑ INCREASED

Downstream

Metastasis Glomus tumors meeting the malignancy criteria metastasize in a substantial minority of cases.

Show evidence (1 reference)

PMID:11145243 SUPPORT Human Clinical

"Five-year cumulative metastatic risk increased significantly for tumors with a deep location (p = 0.005), with a size of more than 2 cm (p = 0.004), and with atypical mitotic figures (p = 0.004)."

Identifies the three features that independently predict metastasis and therefore define malignancy in glomus tumor.

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Histopathology

3

Concentric Perivascular Glomus Cell Arrangement

Uniform, small round glomus cells with central "punched-out" nuclei and sharply defined cell borders arranged in concentric cuffs around capillary-sized vascular channels, recapitulating the modified smooth muscle of the Sucquet-Hoyer canal.

Show evidence (1 reference)

PMID:32604167 SUPPORT Human Clinical

"the cases showed typical features of monomorphic epithelioid to cuboidal cells arranged in solid pattern and encuffing the thin-walled blood vessels"

Describes the defining perivascular cuffing of uniform glomus cells around thin-walled vessels in a 93-tumor cohort.

Nested Growth Pattern

Solid nests and sheets of glomus cells separated by a delicate, collagen-rich, mast-cell-containing stroma; the predominant architecture of the solid glomus tumor variant.

Show evidence (2 references)

PMID:32604167 SUPPORT Human Clinical

"the cases showed typical features of monomorphic epithelioid to cuboidal cells arranged in solid pattern and encuffing the thin-walled blood vessels"

Documents the solid/nested architecture as the typical growth pattern of conventional glomus tumor.

PMID:93364 PARTIAL Human Clinical

"Electron microscopy revealed various types and degrees of degranulation of mast cell granules, and also disclosed a close correlation between mast cells and non-myelinated nerve fibers."

Confirms the mast-cell content of the intervening stroma described here; it does not address the nested architecture itself, hence PARTIAL.

Atypical Mitotic Figures

Atypical mitoses are one of the three independent morphologic predictors of metastasis and are a defining criterion for malignant glomus tumor.

Show evidence (1 reference)

PMID:11145243 SUPPORT Human Clinical

"Five-year cumulative metastatic risk increased significantly for tumors with a deep location (p = 0.005), with a size of more than 2 cm (p = 0.004), and with atypical mitotic figures (p = 0.004)."

Establishes atypical mitotic figures as an independent predictor of metastasis in glomus tumor.

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Pathograph

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Phenotypes

7

Cardiovascular 1

Venous Malformation Venous malformation HP:0012721

Show evidence (1 reference)

PMID:15689436 SUPPORT Human Clinical

"Glomuvenous malformation (GVM) ("familial glomangioma") is a localised cutaneous vascular lesion histologically characterised by abnormal smooth muscle-like "glomus cells" in the walls of distended endothelium lined channels."

Describes the venous-malformation morphology of the inherited multiple form.

Integument 1

Subungual Nodule VERY_FREQUENT Skin nodule HP:0200036

Show evidence (2 references)

PMID:34239958 SUPPORT Human Clinical

"There were 14 patients (82.35%) with subungual tumors"

Documents subungual location in 82% of a hand glomus tumor case series.

PMID:27857505 SUPPORT Human Clinical

"These tumours usually present as a bluish or pinkish red discolouration of the nail plate"

Describes the characteristic bluish subungual appearance of the lesion.

Constitutional 2

Severe Paroxysmal Pain VERY_FREQUENT Pain HP:0012531

Temporal: RECURRENT Severity: SEVERE

Show evidence (1 reference)

PMID:27857505 SUPPORT Human Clinical

"These tumours usually present as a bluish or pinkish red discolouration of the nail plate with classical triad of localised tenderness, severe pain, and cold sensitivity."

Names severe pain as one of the three classical presenting features of glomus tumor.

Pinpoint Tenderness VERY_FREQUENT Pain HP:0012531

Ontology gap - term request needed. This phenotype and "Severe Paroxysmal Pain" both fall back to HP:0012531 Pain, which loses the clinically distinctive feature: point tenderness is the Love pin-test finding and the most sensitive element of the triad, whereas the paroxysmal pain is spontaneous and lancinating. HPO offers no usable alternative. HP:0025283 "Tender" is_a HP:0025280 Pain characteristic, i.e. it sits on the modifier branch rather than under HP:0000118 Phenotypic abnormality, so it cannot serve as a phenotype_term; every other HPO tenderness term is specific to a body site other than the digit (HP:0020226 Nipple tenderness, HP:0100809 Scalp tenderness, HP:6000106 Costovertebral angle tenderness, HP:6000107 Cervical motion tenderness, HP:6001407 Peroneal tendon tenderness). The two phenotypes are therefore held apart by preferred_term until a localized/pinpoint tenderness HPO term exists.

Show evidence (1 reference)

PMID:42181359 SUPPORT Human Clinical

"Localized point tenderness was observed in 10 patients (91%), whereas cold hypersensitivity was present in four patients (36%), and the complete symptom triad was observed in four patients (36%)."

Documents localized point tenderness in 91% of patients, supporting the VERY_FREQUENT (80-100%) frequency band.

Neoplasm 1

Metastasis Neoplasm HP:0002664

Ontology gap - term request needed. HP:0002664 Neoplasm is uninformative inside a neoplasm entry, but HPO has no generic metastasis term: a search of HPO for "metasta" returns exactly one class, HP:0200059 Metastatic angiosarcoma, which is a different disease. The intended meaning (distant metastatic spread, most often to lung and bone) is therefore carried by preferred_term and by the description until HPO gains a generic "Metastasis" phenotype.

Show evidence (1 reference)

PMID:11145243 SUPPORT Human Clinical

"metastasis was observed in 38% of tumors fulfilling the criteria for malignancy"

Quantifies metastatic risk restricted to tumors that meet the malignancy criteria.

Other 2

Cold Hypersensitivity FREQUENT Allodynia HP:0012533

Show evidence (1 reference)

PMID:42181359 SUPPORT Human Clinical

"Localized point tenderness was observed in 10 patients (91%), whereas cold hypersensitivity was present in four patients (36%), and the complete symptom triad was observed in four patients (36%)."

Quantifies cold hypersensitivity in 36% of a consecutive hand glomus tumor series, supporting the FREQUENT (30-79%) frequency band.

Gastric (Visceral) Glomus Tumor Neoplasm of the stomach HP:0006753

No frequency band is asserted. The visceral share of all glomus tumors cannot be estimated from the available literature, which consists of single-institution surgical-pathology series (11 and 21 cases) with no common denominator; a numeric or banded frequency here would be fabricated.

Show evidence (4 references)

PMID:32337257 SUPPORT Human Clinical

"The most common location was the antrum, the mean age of patients was 49.3 years, and the mean tumor size was 2.1 cm."

Establishes the gastric antrum as the characteristic visceral site in a 21-case surgical series.

PMID:32337257 SUPPORT Human Clinical

"The majority of GGTs are benign, and local surgery achieving complete resection is the most effective treatment method."

Establishes the benign behaviour and surgical management of the gastric presentation, mirroring the acral lesion.

PMID:24817939 SUPPORT Human Clinical

"Our results show that GTs in the stomach are histologically and immunophenotypically fully comparable with the glomus tumors of peripheral soft tissues."

Confirms that the gastric lesion is the same entity as the soft tissue glomus tumor rather than a separate, similarly named tumor - the point that justifies curating it inside this entry.

+ 1 more reference

🧬

Genetic Associations

6

MIR143-NOTCH2 fusion

Gene: NOTCH2 hgnc:7882 variant_origin: SOMATIC

Show evidence (1 reference)

PMID:32604167 SUPPORT Human Clinical

"rearrangements of NOTCH genes are seen in over half of GT, with NOTCH2-MIR143 being the most common fusion (73%)"

Establishes NOTCH2-MIR143 as the predominant fusion in a large glomus tumor cohort.

MIR143-NOTCH3 fusion

Gene: NOTCH3 hgnc:7883 variant_origin: SOMATIC

Show evidence (1 reference)

PMID:23999936 SUPPORT Human Clinical

"NOTCH3 rearrangements were identified in 9% of GTs, all present in benign soft tissue GT, one case being fused to MIR143"

Documents NOTCH3 as a less frequent fusion partner restricted to benign soft tissue tumors.

BRAF V600E

Gene: BRAF hgnc:1097 variant_origin: SOMATIC

Show evidence (1 reference)

PMID:40976119 SUPPORT Human Clinical

"Pathway enrichment analysis revealed KRAS mutations were predominant in distal GT, while BRAF V600E mutations were more prevalent in proximal locations."

Documents BRAF V600E in glomus tumor and its anatomic enrichment.

KRAS

Gene: KRAS hgnc:6407 variant_origin: SOMATIC

Show evidence (1 reference)

PMID:40976119 SUPPORT Human Clinical

"Pathway enrichment analysis revealed KRAS mutations were predominant in distal GT, while BRAF V600E mutations were more prevalent in proximal locations."

Documents somatic KRAS mutation in glomus tumor and its enrichment in distal lesions, the mirror image of the BRAF V600E distribution.

NF1

Gene: NF1 hgnc:7765 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:19738042 SUPPORT Human Clinical

"Glomus tumors of the fingers or toes should be considered as part of the tumor spectrum of NF1."

Establishes germline NF1 as a susceptibility genotype for digital glomus tumor.

GLMN

Gene: GLMN hgnc:14373 variant_origin: GERMLINE

Show evidence (1 reference)

PMID:15689436 SUPPORT Human Clinical

"This finding suggests that GVM results from complete localised loss of function and explains the paradominant mode of inheritance."

Establishes GLMN loss of function and the paradominant inheritance model for glomuvenous malformation.

💊

Medical Actions

4

Complete Surgical Excision

Category: Therapeutic Action: Excision NCIT:C15232

Complete surgical excision, typically via a transungual or lateral subperiosteal approach for subungual lesions, is the definitive treatment for localized glomus tumor. It produces prompt and durable relief of pain; incomplete excision is the principal cause of symptomatic recurrence.

Mechanism Target:

INHIBITS Glomus Cell Proliferation Around Distorted Vascular Channels — Excision physically removes the proliferating glomus cell mass and with it the nociceptor-rich stroma responsible for the pain syndrome.

Show evidence (1 reference)

PMID:34239958 SUPPORT Human Clinical

"experienced complete symptomatic relief within 2-4 weeks after surgical excision"

Removal of the proliferating mass abolishes the pain syndrome in every patient, demonstrating that the excised node is the mechanistic source of the symptoms.

Show evidence (3 references)

PMID:34239958 SUPPORT Human Clinical

"experienced complete symptomatic relief within 2-4 weeks after surgical excision"

Reports complete symptomatic relief in all 17 patients after excision, with no recurrence at one year.

PMID:27857505 SUPPORT Human Clinical

"Complete surgical excision is a must to get complete relief from the symptoms and to avoid recurrence."

States that completeness of excision determines both symptom relief and freedom from recurrence.

PMID:41693210 SUPPORT Human Clinical

"While complete surgical excision remains the standard curative treatment for localized disease"

Confirms complete excision as the standard curative therapy for localized glomus tumor.

MEK Inhibition for NF1-Deficient Tumors

Category: Therapeutic Action: Targeted Therapy NCIT:C93352

Agent: selumetinib CHEBI:90227

For NF1-deficient glomus tumors there is no BRAF kinase to inhibit, so the proposed systemic strategy is direct MEK blockade downstream of the unrestrained RAS. This is an investigational, mechanism-derived rationale rather than an established standard: it is put forward in narrative review for multifocal, metastatic, or surgically challenging cases, and no glomus-tumor-specific trial or response series supports it yet. Selumetinib is named as the exemplar MEK inhibitor because it is the agent approved in NF1-associated plexiform neurofibroma, not because it has been tested in glomus tumor.

Mechanism Target:

INHIBITS Constitutive Mitogenic Pathway Activation — MEK inhibition blocks the RAS-MAPK cascade immediately downstream of the RAS node that neurofibromin loss leaves unrestrained.

Show evidence (1 reference)

PMID:41693210 PARTIAL Human Clinical

"molecular insights have spurred investigation into targeted agents, including MEK inhibitors for NF1-deficient tumors and immunotherapy"

States the MEK-inhibition rationale for NF1-deficient glomus tumors; it is framed as investigation spurred by molecular insight, not as demonstrated efficacy, hence PARTIAL.

Show evidence (2 references)

PMID:41693210 PARTIAL Human Clinical

"Such systemic therapies are particularly relevant for multifocal, metastatic, or surgically challenging cases."

Scopes the systemic-therapy indication to unresectable/multifocal disease; no efficacy data are reported, so this remains investigational.

PMID:19738042 SUPPORT In Vitro

"RAS mitogen-activated protein kinase hyperactivation was observed in cultured NF1(-/-) glomus cells, reflecting a lack of inhibition of the pathway by functional neurofibromin, the protein product of NF1."

Supplies the mechanistic target: cultured NF1-null glomus cells show the RAS-MAPK hyperactivation that a MEK inhibitor would suppress.

BRAF and MEK Inhibition

Category: Therapeutic Action: Targeted Therapy NCIT:C93352

Agent: encorafenib NCIT:C98283 binimetinib CHEBI:145371

For metastatic malignant glomus tumor harboring BRAF p.Val600Glu, combined BRAF and MEK inhibition with encorafenib plus binimetinib has produced a complete clinical and morpho-metabolic response. Evidence is limited to case reports, and conventional chemotherapy is poorly effective in this setting.

Mechanism Target:

INHIBITS Constitutive Mitogenic Pathway Activation — Encorafenib inhibits the mutant BRAF kinase and binimetinib blocks downstream MEK, shutting off the constitutive RAS-MAPK output that drives proliferation.

Show evidence (1 reference)

PMID:39392364 SUPPORT Human Clinical

"The BRAF V600E mutation has been identified in a subset of malignant GT, highlighting a promising therapeutic target."

Identifies BRAF V600E as the actionable target of the combination in malignant glomus tumor.

Show evidence (1 reference)

PMID:39392364 PARTIAL Human Clinical

"Here, we report the impressive clinical and morpho-metabolic response of a metastatic BRAF V600E-mutated glomangiosarcoma after treatment with encorafenib and binimetinib."

Single-case evidence of response; supportive but not sufficient to establish standard-of-care status.

Symptom-Directed Surveillance for Digital Glomus Tumour in NF1

Category: Screening Action: periodic clinical assessment with nail-bed inspection and symptom enquiry Ontology label: Physical Examination NCIT:C20989

Digital glomus tumour is part of the NF1 tumour spectrum and is the most under-recognised member of it, so the 2023 ERN GENTURIS NF1 tumour surveillance guideline manages it by symptom-directed clinical vigilance rather than by imaging. Adults with NF1 are assessed clinically at least once every three years, and every visit includes history taking and, for this tumour, direct questioning about localised tenderness, severe paroxysmal pain and cold sensitivity in the fingers and toes together with visual inspection of the nail beds and palpation. No routine imaging of asymptomatic digits is recommended. The rationale is diagnostic delay rather than mortality: patients frequently live with the pain for years without the diagnosis being considered, so the yield comes from asking. Because NF1-associated lesions are more often multifocal and both local recurrence and metachronous tumours are common, excision of one lesion does not end surveillance.

Show evidence (4 references)

PMID:36684394 PARTIAL Human Clinical

"Given the oncogenic potential, long-term surveillance is important in patients with NF1."

The European Reference Network guideline that frames tumour surveillance as standard care in NF1. PARTIAL because the glomus-specific recommendations sit in the guideline's full text rather than its abstract (see notes).

PMID:20530151 SUPPORT Human Clinical

"Glomus tumours in NF1 are more common than previously recognised and NF1 patients should be specifically queried about fingertip or toe pain."

States the surveillance action itself - direct symptom enquiry in every NF1 patient - and is the primary series the GENTURIS guideline cites for its glomus tumour recommendations.

PMID:20530151 SUPPORT Human Clinical

"There is often a delay in diagnosis of many years and clinical suspicion is key to diagnosis, although magnetic resonance imaging may be useful in some scenarios."

Supplies the rationale for symptom-directed vigilance rather than routine imaging, and the reason surveillance is worthwhile at all.

+ 1 more reference

🔬

Biochemical Markers

3

Smooth Muscle Actin Expression

Show evidence (1 reference)

PMID:1848411 SUPPORT Human Clinical

"all tumors were immunoreactive for muscle-specific actin, but only two expressed desmin"

Documents uniform muscle-specific actin positivity with only variable desmin expression, the characteristic glomus tumor immunophenotype.

Desmin Expression

Show evidence (1 reference)

PMID:1848411 SUPPORT Human Clinical

"all tumors were immunoreactive for muscle-specific actin, but only two expressed desmin"

Shows desmin expression in only 2 of 6 glomus tumors, supporting its variable-to-negative status.

Contractile Smooth Muscle Marker Expression (Smoothelin and h-Caldesmon)

Show evidence (1 reference)

PMID:27184662 SUPPORT Human Clinical

"Smoothelin expression in glomic cells indicates that they are contractile smooth muscle cells"

Immunohistochemical panel including h-caldesmon establishes the contractile smooth muscle phenotype of glomus cells.

🔀

Differential Diagnoses

8

Conditions with similar clinical presentations that must be differentiated from Glomus Tumor:

Jugulotympanic paraganglioma ("glomus jugulare" / "glomus tympanicum") Not Yet Curated MONDO:0021064

Overlapping Features This is a NAMING COLLISION, not a biological differential. The skull-base and middle-ear tumours historically called "glomus jugulare" and "glomus tympanicum" are PARAGANGLIOMAS and are NOT glomus tumours in the sense of this entry. They arise from neural-crest-derived parasympathetic paraganglia of the jugular bulb and tympanic plexus, are neuroendocrine (chromogranin / synaptophysin positive, with S100/SOX10-positive sustentacular cells), are associated with germline SDHx variants, may be catecholamine-secreting, and are managed by skull-base surgery or stereotactic radiosurgery. They share nothing with the pericytic MIR143-NOTCH-driven soft-tissue glomus tumour except the nineteenth-century use of "glomus" for a vascular body. Anyone reaching this entry from a "glomus jugulare" query has the wrong entity: see MONDO:0021064 (jugulotympanic paraganglioma) instead.

Distinguishing Features

Anatomic site is the jugular foramen / middle ear rather than the acral soft tissue or nail bed
Neuroendocrine chief-cell morphology with chromogranin and synaptophysin expression, and S100/SOX10-positive sustentacular cells; glomus tumour is S100-negative and actin-positive
Derived from neural-crest paraganglia, not from perivascular modified smooth muscle
Germline SDHx predisposition; no MIR143-NOTCH fusion
May secrete catecholamines and present with pulsatile tinnitus and lower cranial neuropathy, not with the paroxysmal-pain/cold-sensitivity triad

Show evidence (2 references)

PMID:42349676 SUPPORT Human Clinical

"Jugulotympanic paragangliomas (JTPs) are rare, hypervascular skull base tumors."

Confirms that the entity clinically called "glomus jugulare" is a jugulotympanic paraganglioma of the skull base - a different disease from the acral pericytic glomus tumour modelled here.

PMID:20530151 SUPPORT Human Clinical

"Glomus bodies are thermoregulatory shunts concentrated in the dermis of the fingertips and other peripheral sites subject to excessive cold and should be distinguished from unrelated adrenal and extra-adrenal paragangliomas, also commonly called "glomus tumors.""

The glomus-tumour literature itself instructs readers to keep the thermoregulatory glomus body distinct from the unrelated paragangliomas that share the "glomus tumour" name - an authoritative statement of the naming collision this differential exists to prevent.

Myopericytoma Not Yet Curated MONDO:0017349

Overlapping Features A member of the same pericytic/perivascular myoid tumour family, showing concentric perivascular growth of myoid cells. Morphologic overlap with glomus tumour is substantial, and the two are separated most cleanly at the molecular level: myopericytoma and myofibroma carry PDGFRB mutations whereas glomus tumour carries NOTCH fusions.

Distinguishing Features

Concentric multilayered perivascular myoid whorls rather than sheets of uniform round glomus cells with sharply defined borders
PDGFRB-mutant rather than NOTCH-fusion positive
Usually painless, in contrast to the paroxysmal-pain triad of subungual glomus tumour

Show evidence (2 references)

PMID:32604167 SUPPORT Human Clinical

"They share variable histologic overlap with other tumors in the pericytic family including myofibroma (MF), myopericytoma (MP) and angioleiomyoma (AL)."

Names myopericytoma as a histologic mimic within the pericytic family.

PMID:32604167 SUPPORT Human Clinical

"the emerging genetic data suggest a dichotomy of the perivascular myoid tumor spectrum into 2 categories: PDGFRB-mutant MF and MP and NOTCH-fusion positive GT."

Supplies the molecular discriminator that separates myopericytoma / myofibroma from glomus tumour.

Angioleiomyoma Not Yet Curated MONDO:0006646

Overlapping Features A benign dermal or subcutaneous neoplasm of well-differentiated smooth muscle arranged around numerous vessels. Like glomus tumour it is a painful vascular-rich subcutaneous nodule of the extremities, so it is a genuine clinical as well as histologic mimic; unlike glomus tumour its cells are frankly spindled and strongly desmin-positive.

Distinguishing Features

Intersecting fascicles of elongated, cigar-shaped smooth muscle cells rather than rounded glomus cells with punched-out nuclei
Diffusely and strongly desmin-positive; glomus tumour is desmin-negative or only focally positive
Not NOTCH-fusion driven
Typically a deeper subcutaneous lower-limb nodule rather than a subungual lesion

Show evidence (2 references)

PMID:32604167 SUPPORT Human Clinical

"They share variable histologic overlap with other tumors in the pericytic family including myofibroma (MF), myopericytoma (MP) and angioleiomyoma (AL)."

Names angioleiomyoma as a histologic mimic within the pericytic family.

PMID:1848411 PARTIAL Human Clinical

"all tumors were immunoreactive for muscle-specific actin, but only two expressed desmin"

Supplies the glomus-tumour side of the desmin discriminator (variable to negative); the angioleiomyoma comparison is standard diagnostic practice not measured in this paper, hence PARTIAL.

GLI1-altered soft tissue tumour (GLI1-fused or GLI1-amplified)

Overlapping Features The most contemporary addition to the pericytic/perivascular differential. A distinct group of soft tissue neoplasms defined either by GLI1 gene fusions (ACTB, MALAT1 or PTCH1 partners) or by GLI1 amplification with CDK4 and MDM2 co-amplification shows monomorphic ovoid-to-epithelioid cells in a nested-trabecular pattern separated by thin septa and a delicate capillary network. The authors of the defining series call this architecture highly reminiscent of glomus tumour and list glomus tumour/myopericytoma explicitly among the differential diagnoses. The distinction is prognostic, not academic: unlike conventional glomus tumour these are malignant soft tissue tumours, with high mitotic counts, necrosis, lymphovascular invasion and documented lymph node and lung metastases, and they cannot be separated from glomus tumour on morphology alone.

Distinguishing Features

GLI1 gene fusion, or GLI1 amplification usually with CDK4 and MDM2 co-amplification, rather than a MIR143-NOTCH fusion
Frequent S100 positivity and an inconsistent immunoprofile (CD56, SMA, pan-CK variably positive); glomus tumour is consistently actin-positive and S100-negative
High mitotic count and necrosis in a substantial minority, with lymphovascular invasion
Malignant behaviour is the rule rather than the rare exception it is in glomus tumour

Show evidence (3 references)

PMID:31189998 SUPPORT Human Clinical

"Glomus tumors are consistently positive for actin and show the miR143-NOTCH2 gene fusion in most cases"

The defining GLI1 series states the discriminator from the glomus-tumour side - consistent actin positivity plus the MIR143-NOTCH2 fusion - when setting out its own differential diagnosis.

PMID:31189998 SUPPORT Human Clinical

"FISH showed GLI1 (12q13.3) gene amplification in all 10 cases, with co-amplification of CDK4 (12q14.1) in nine (90%) and MDM2 (12q15) in eight (80%) cases."

Supplies the molecular signature that separates this group from glomus tumour.

PMID:31189998 SUPPORT Human Clinical

"No consistent immunoprofile was detected, with positivity for CD56 (six cases), S100 (four cases), SMA (two cases), and pan-CK (one case)."

Documents the inconsistent, frequently S100-positive immunoprofile, the inverse of the uniform actin-positive, S100-negative glomus tumour phenotype.

Solitary fibrous tumour (formerly haemangiopericytoma) MONDO:0016238

Overlapping Features Historically confused with glomus tumour because "haemangiopericytoma" was once used for any perivascular-patterned tumour. Solitary fibrous tumour is now defined by the NAB2-STAT6 fusion with nuclear STAT6 expression and CD34 positivity, and is a fibroblastic rather than pericytic lesion; the staghorn-vessel pattern it shares with glomus tumour is a non-specific architectural feature.

Distinguishing Features

Patternless spindle-cell proliferation with ropey collagen and staghorn vessels, not uniform round perivascular glomus cells
Nuclear STAT6 (NAB2-STAT6 fusion) and CD34 positive; glomus tumour is STAT6/CD34 negative and SMA positive
Fibroblastic lineage, not pericytic; no NOTCH fusion
Typically a deep-seated or serosal mass, painless, without the cold-sensitivity triad

Show evidence (3 references)

PMID:24030747 SUPPORT Human Clinical

"In conclusion, STAT6 is a highly sensitive and almost perfectly specific immunohistochemical marker for SFT and can be helpful to distinguish this tumor type from histologic mimics."

Validates nuclear STAT6 as the discriminator that separates solitary fibrous tumour from its histologic mimics, glomus tumour among them.

PMID:24030747 SUPPORT Human Clinical

"Fifty-nine of 60 SFT cases (98%) showed nuclear expression of STAT6, which was usually diffuse and intense. All other tumor types were negative for STAT6, except for three dedifferentiated liposarcomas and one deep fibrous histiocytoma, which showed weak staining."

Quantifies the operating characteristics of the STAT6 discriminator across 231 soft tissue tumours, establishing that a STAT6-negative perivascular lesion is not a solitary fibrous tumour.

PMID:31189998 PARTIAL Human Clinical

"Glomus tumors are consistently positive for actin and show the miR143-NOTCH2 gene fusion in most cases"

Supplies the glomus-tumour side of the discriminator (actin positivity plus MIR143-NOTCH2 fusion) in a paper that discusses solitary fibrous tumour and glomus tumour together on the same differential; it does not itself compare the two head to head, hence PARTIAL.

Eccrine spiradenoma Not Yet Curated MONDO:0003448

Overlapping Features A benign sweat-gland adnexal neoplasm and one of the classic causes of a small, exquisitely painful dermal nodule. It sits alongside glomus tumour on the standard differential for a painful cutaneous or subungual nodule, but is an epithelial (basaloid) tumour rather than a perivascular myoid one.

Distinguishing Features

Basaloid epithelial nodules with two cell populations and scattered lymphocytes, not perivascular myoid cells
Cytokeratin-positive and SMA-negative in the neoplastic cells, the inverse of the glomus tumour immunophenotype
No cold hypersensitivity or Hildreth response
More often trunk or proximal-extremity dermis than subungual

Show evidence (1 reference)

PMID:27857505 SUPPORT Human Clinical

"differential diagnosis of other painful tumours, such as leiomyoma, eccrine spiradenoma, haemangioma, neuroma, osteochondroma, or mucous cyst should always be kept in mind while evaluating a patient with severe pain in the tip of the finger."

Places eccrine spiradenoma explicitly on the differential for a painful fingertip lesion, together with the other painful-tumour mimics.

Other painful acral lesions (leiomyoma, haemangioma, neuroma, osteochondroma, mucous cyst)

Overlapping Features A cluster of lesions that share the presenting complaint - severe pain at the fingertip - but not the mechanism. They are grouped here because the review literature enumerates them together as the standing differential for a painful digital lesion, and because diagnostic delay in glomus tumour is typically caused by one of them being assumed instead.

Distinguishing Features

None reproduces the full triad of paroxysmal pain, pinpoint tenderness and cold hypersensitivity with a positive Hildreth response
Contrast-enhanced high-resolution MRI distinguishes most of them from the avidly enhancing, T2-hyperintense glomus tumour
Definitive separation is histopathologic

Show evidence (1 reference)

PMID:27857505 SUPPORT Human Clinical

"differential diagnosis of other painful tumours, such as leiomyoma, eccrine spiradenoma, haemangioma, neuroma, osteochondroma, or mucous cyst should always be kept in mind while evaluating a patient with severe pain in the tip of the finger."

Enumerates the standing differential for a painful fingertip lesion.

Glomuvenous malformation (GLMN-related) Not Yet Curated MONDO:0007672

Overlapping Features Modelled in this entry as a subtype rather than a wholly separate disease, but the boundary matters and is easy to blur. Sporadic solitary glomus tumour is a somatic, fusion-driven NEOPLASM; glomuvenous malformation is an inherited GLMN-related vascular MALFORMATION in which a somatic second hit (usually acquired uniparental isodisomy of 1p) unmasks the germline allele locally. They are not two presentations of one lesion, and evidence about one must not be transferred to the other.

Distinguishing Features

Multiple, multifocal, compressible blue-purple plaques rather than a solitary subungual nodule
Much less painful, and pain is not paroxysmal or cold-provoked
Germline GLMN loss of function with a somatic second hit (paradominant), not a MIR143-NOTCH fusion
Dilated venous channels with only a few layers of glomus cells, rather than solid sheets of glomus cells

Show evidence (2 references)

PMID:15689436 SUPPORT Human Clinical

"Glomuvenous malformation (GVM) ("familial glomangioma") is a localised cutaneous vascular lesion histologically characterised by abnormal smooth muscle-like "glomus cells" in the walls of distended endothelium lined channels."

Defines GVM as a vascular lesion with glomus cells in the channel walls, distinct in architecture from the solid sporadic glomus tumour.

PMID:23375657 SUPPORT Human Clinical

"This finding demonstrates that a double hit is needed to trigger formation of a GVM."

Establishes the germline-plus-somatic two-hit genetics that distinguishes GVM from the purely somatic sporadic glomus tumour.

🔬

Clinical Trials

1

NCT03422679 PHASE_I TERMINATED

Dose-escalation study of CB-103, an oral pan-NOTCH transcription-complex inhibitor, in adults with locally advanced or metastatic solid tumours and haematological malignancies characterised by NOTCH pathway alterations. Malignant glomus tumor is one of the registry-indexed conditions, making this the first trial to prospectively select glomus tumors on the basis of their MIR143-NOTCH driver. Seventy-nine patients enrolled overall and the study was stopped early; the ClinicalTrials.gov record gives the reason for stopping as a business reason, not demonstrated inefficacy. The peer-reviewed phase I report found a manageable safety profile and pharmacodynamic evidence of Notch target-gene downregulation, but limited single-agent antitumor activity: no objective responses and stable disease in 49%. The population was dominated by adenoid cystic carcinoma (40 of 79, 51%) and no glomus-tumor-specific outcome was reported, so these basket-level results must not be attributed to the glomus subgroup in either direction.

Target Phenotypes: Neoplasm HP:0002664

Show evidence (3 references)

clinicaltrials:NCT03422679 PARTIAL Human Clinical

"investigate the safety, tolerability and preliminary efficacy of CB-103"

Registry record for the NOTCH-pathway-selected basket trial that lists malignant glomus tumor among its conditions; the study was terminated, so it supports the therapeutic rationale rather than any efficacy claim.

PMID:37712875 PARTIAL Human Clinical

"CB-103 had a manageable safety profile and biological activity but limited clinical antitumor activity as monotherapy in this first-in-human study."

The peer-reviewed phase I publication behind this registry record. It establishes tolerability and on-target biological activity but not efficacy, which is why the pan-NOTCH strategy remains a rationale rather than a treatment for malignant glomus tumor.

PMID:37712875 PARTIAL Human Clinical

"There were no objective responses, but 37 (49%) had stable disease; including 23 of 40 (58%) patients with ACC."

Gives the basket-level outcome. Adenoid cystic carcinoma dominated the cohort (40 of 79) and no glomus-tumor-specific response is reported, so this figure bounds what may be claimed for glomus tumor rather than supporting or refuting activity in it.

{ }

Source YAML

click to show

name: Glomus Tumor
creation_date: '2026-07-31T00:00:00Z'
description: >-
  Glomus tumor is a rare, usually benign pericytic (perivascular) mesenchymal
  neoplasm composed of cells that recapitulate the modified smooth muscle cells
  of the glomus body, a specialized arteriovenous anastomosis of the dermis that
  participates in thermoregulation. Most lesions are small, solitary, and arise
  in the distal extremities, classically in the subungual nail bed, where they
  produce the diagnostic clinical triad of severe paroxysmal pain, cold
  hypersensitivity, and exquisite pinpoint tenderness. The disease is not
  confined to skin: deep soft tissue and visceral tumors also occur, most
  characteristically in the gastric wall, where the lesion is the same entity
  histologically and immunophenotypically but presents as a submucosal antral
  mass or with gastrointestinal bleeding rather than with the acral pain triad.
  Histologically the tumor consists of sheets and nests of uniform, round,
  "punched-out" glomus cells with sharply defined cell borders arranged
  concentrically around branching, distorted vascular channels. The
  immunophenotype is that of a contractile
  modified smooth muscle cell: diffuse smooth muscle actin and h-caldesmon
  positivity with pericellular type IV collagen, and negativity for S100 protein
  and cytokeratin, with desmin only variably expressed. Recurrent
  MIR143::NOTCH gene-family fusions (MIR143 juxtaposed to NOTCH1, NOTCH2, or
  NOTCH3) are found in over half of glomus tumors and are the characteristic
  somatic driver; a separate subset carries activating BRAF V600E or NF1/RAS
  pathway lesions that converge on constitutive RAS-MAPK signaling. Notably, the
  common subungual tumors are largely fusion-negative, implying a still-undefined
  alternative pathogenesis. A familial multiple form, glomuvenous malformation
  (familial glomangioma), is caused by germline loss-of-function variants in GLMN
  (glomulin) acting through a paradominant two-hit mechanism, most often
  completed by somatic acquired uniparental isodisomy of chromosome 1p.
  Malignant glomus tumors are rare and defined morphologically by deep location
  with size greater than 2 cm, atypical mitotic figures, or moderate-to-high
  nuclear grade with brisk mitotic activity. Complete surgical excision is
  curative for benign lesions and produces prompt, durable relief of pain.
categories:
- Rare Cancer
- Soft Tissue Tumor
parents:
- pericytic neoplasm
- soft tissue neoplasm
disease_term:
  preferred_term: glomus tumor
  term:
    id: MONDO:0018327
    label: glomus tumor
has_subtypes:
- name: Solid Glomus Tumor
  display_name: Solid Glomus Tumor
  description: >-
    The most common histologic variant, characterized by nests and sheets of
    uniform glomus cells with relatively inconspicuous vasculature. Typically
    solitary, subungual, and painful.
  evidence:
  - reference: PMID:27184662
    reference_title: Smoothelin and WT-1 expression in glomus tumors and glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We assessed 9 cases of solid glomus tumors (SGT), 8 cases of glomus tumors
      with vascular ectasia (VEGT), 2 cases of glomangiomyomas (GMM) and 6 cases
      of glomuvenous malformation (GM).
    explanation: >-
      An immunohistochemical series that enumerates the recognized histologic
      variants of glomus tumor, including this one.
- name: Glomangioma
  display_name: Glomangioma (Glomuvenous Variant)
  description: >-
    A variant dominated by dilated, cavernous venous-like vascular channels
    rimmed by only a few layers of glomus cells. Glomangiomas account for the
    great majority of multiple and familial lesions.
  evidence:
  - reference: PMID:27184662
    reference_title: Smoothelin and WT-1 expression in glomus tumors and glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We assessed 9 cases of solid glomus tumors (SGT), 8 cases of glomus tumors
      with vascular ectasia (VEGT), 2 cases of glomangiomyomas (GMM) and 6 cases
      of glomuvenous malformation (GM).
    explanation: >-
      An immunohistochemical series that enumerates the recognized histologic
      variants of glomus tumor, including this one.
- name: Glomangiomyoma
  display_name: Glomangiomyoma
  description: >-
    The least common variant, in which glomus cells show transition to elongated,
    frankly mature smooth muscle cells around the vascular channels.
  evidence:
  - reference: PMID:27184662
    reference_title: Smoothelin and WT-1 expression in glomus tumors and glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We assessed 9 cases of solid glomus tumors (SGT), 8 cases of glomus tumors
      with vascular ectasia (VEGT), 2 cases of glomangiomyomas (GMM) and 6 cases
      of glomuvenous malformation (GM).
    explanation: >-
      An immunohistochemical series that enumerates the recognized histologic
      variants of glomus tumor, including this one.
- name: Glomuvenous Malformation
  display_name: Glomuvenous Malformation (Familial Multiple Glomangioma)
  description: >-
    An inherited, multifocal cutaneous vascular malformation caused by
    loss-of-function variants in GLMN (glomulin). Lesions are typically multiple,
    blue-purple, compressible plaques or nodules that are less painful than
    solitary solid glomus tumors, and they are inherited in an autosomal dominant
    pattern with incomplete penetrance explained by a paradominant somatic second
    hit.
  evidence:
  - reference: PMID:15689436
    reference_title: 'Four common glomulin mutations cause two thirds of glomuvenous malformations ("familial glomangiomas"): evidence for a founder effect.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomuvenous malformation (GVM) ("familial glomangioma") is a localised
      cutaneous vascular lesion histologically characterised by abnormal smooth
      muscle-like "glomus cells" in the walls of distended endothelium lined
      channels.
    explanation: >-
      Defines glomuvenous malformation as the inherited, glomus-cell-lined
      vascular lesion subtype.
- name: Glomangiomatosis
  display_name: Glomangiomatosis
  description: >-
    A rare variant in the Folpe classification showing the histologic features of
    diffuse angiomatosis together with an excess of glomus cells. Despite its
    infiltrative, angiomatosis-like growth it behaves benignly: no case in the
    defining series metastasized.
  evidence:
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomangiomatosis: Tumors with histologic features of diffuse angiomatosis
      and excess glomus cells.
    explanation: >-
      States the Folpe definition of glomangiomatosis as a distinct category in
      the glomus tumor classification scheme.
- name: Symplastic Glomus Tumor
  display_name: Symplastic Glomus Tumor
  description: >-
    A tumor showing high nuclear grade (marked nuclear atypia/pleomorphism) in
    the absence of any other malignant feature. This is explicitly NOT a
    malignant glomus tumor: in the defining series, high nuclear grade alone was
    not associated with metastasis, and no symplastic tumor metastasized. The
    atypia is regarded as degenerative rather than as evidence of malignancy.
  evidence:
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Symplastic glomus tumor: Tumors with high nuclear grade in the absence of
      any other malignant feature.
    explanation: >-
      States the Folpe definition of the symplastic category.
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      metastatic disease was not seen in any specimen classified as symplastic
      glomus tumor, glomus tumor of uncertain malignant potential, or
      glomangiomatosis.
    explanation: >-
      Establishes that the symplastic category is prognostically benign, which is
      why it must not be collapsed into malignant glomus tumor.
- name: Uncertain Malignant Potential
  display_name: Glomus Tumor of Uncertain Malignant Potential
  description: >-
    The Folpe intermediate category: tumors that lack the criteria for malignant
    glomus tumor or symplastic glomus tumor but have high mitotic activity with
    superficial location only, or large size only, or deep location only. That
    is, exactly one worrisome feature is present rather than the qualifying
    combination. No tumor in this category metastasized in the defining series.
  evidence:
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumor of uncertain malignant potential: Tumors that lack criteria
      for malignant glomus tumor or symplastic glomus tumor but have high mitotic
      activity and superficial location only, or large size only, or deep
      location only.
    explanation: >-
      States the Folpe definition of the uncertain-malignant-potential category
      and its exact feature combination.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Seventy-two cases were benign, 17 cases were malignant and 4 were of
      uncertain malignant potential.
    explanation: >-
      Independently confirms that the uncertain-malignant-potential category is
      applied in contemporary molecular-pathology cohorts, at roughly 4% of
      tumors.
- name: Malignant Glomus Tumor
  display_name: Malignant Glomus Tumor (Glomangiosarcoma)
  description: >-
    A rare aggressive form defined by deep location together with size greater
    than 2 cm, the presence of atypical mitotic figures, or moderate-to-high
    nuclear grade with at least 5 mitotic figures per 50 high-power fields.
    Capable of local recurrence and distant metastasis. Note that the three
    qualifying criteria are alternatives, and that high nuclear grade alone
    (symplastic glomus tumor) or a single worrisome feature alone (uncertain
    malignant potential) does NOT meet this definition.
  evidence:
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Malignant glomus tumor: Tumors with a deep location and a size of more than
      2 cm, or atypical mitotic figures
    explanation: >-
      States the consensus morphologic criteria that define the malignant glomus
      tumor subtype.
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      High nuclear grade alone, infiltrative growth, and vascular space
      involvement were not associated with metastasis.
    explanation: >-
      Bounds the malignancy definition: the features that do NOT by themselves
      qualify a tumor as malignant, which is why symplastic tumors are a separate
      category.
prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: RARE
  notes: >-
    No population-based incidence or prevalence estimate exists for glomus tumor.
    Frequently repeated proportions (e.g. "1-5% of hand soft tissue tumors")
    derive from surgical-pathology archives, not population registries, and are
    not interpretable as prevalence. The only defensible structured statement is
    the qualitative RARE band; a numeric rate is deliberately omitted rather than
    fabricated. See the KNOWLEDGE_GAP discussion attached to this entry.
  evidence:
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumours are rare benign vascular neoplasms commonly found in the
      hand particularly in subungual region.
    explanation: >-
      Supports the qualitative RARE occurrence band without asserting a rate.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumors (GT) are rare mesenchymal neoplasms composed of cells
      resembling the perivascular modified smooth muscle cells of the normal
      glomus body.
    explanation: >-
      Independent confirmation of rarity from a large molecular-pathology series.
pathophysiology:
- name: MIR143-NOTCH Gene Fusion
  biological_scale: MOLECULAR
  role: trigger
  description: >-
    Recurrent somatic rearrangements juxtapose the MIR143 locus in band 5q32 to a
    NOTCH gene family member. NOTCH2 (1p13) is by far the most frequent partner,
    with NOTCH1 (9q34) and NOTCH3 also reported. The rearrangement places a
    truncated NOTCH segment under control of the highly expressed MIR143 locus,
    producing marked overexpression of a ligand-independent NOTCH product in the
    perivascular myoid tumor cell. NOTCH2 and NOTCH3 are the physiologic
    regulators of vascular smooth muscle development, which is consistent with a
    perivascular myoid lineage for the resulting neoplasm. Importantly, the
    common subungual glomus tumor subset is largely fusion-negative, indicating
    that an alternative, still-undefined pathogenesis operates at that site.
  cell_types:
  - preferred_term: glomus cell (modified perivascular smooth muscle cell)
    term:
      id: CL:0000192
      label: smooth muscle cell
  genes:
  - preferred_term: NOTCH2
    term:
      id: hgnc:7882
      label: NOTCH2
  - preferred_term: NOTCH3
    term:
      id: hgnc:7883
      label: NOTCH3
  - preferred_term: NOTCH1
    term:
      id: hgnc:7881
      label: NOTCH1
  - preferred_term: MIR143
    term:
      id: hgnc:31530
      label: MIR143
  biological_processes:
  - preferred_term: Notch signaling pathway
    modifier: ABNORMAL
    term:
      id: GO:0007219
      label: Notch signaling pathway
  evidence:
  - reference: PMID:23999936
    reference_title: Novel MIR143-NOTCH fusions in benign and malignant glomus tumors.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A gene fusion involving MIR143 in band 5q32 was identified in both GTs with
      either NOTCH2 in 1p13 in GT1 or NOTCH1 in 9q34 in GT2
    explanation: >-
      Landmark RNA-sequencing study identifying the MIR143-NOTCH fusion as the
      recurrent driver rearrangement of glomus tumor.
  - reference: PMID:23999936
    reference_title: Novel MIR143-NOTCH fusions in benign and malignant glomus tumors.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Overall NOTCH2 gene rearrangements were identified in 52% of GT, including
      all malignant cases
    explanation: >-
      Quantifies NOTCH2 rearrangement prevalence and its presence in all
      malignant tumors of the series.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      rearrangements of NOTCH genes are seen in over half of GT, with
      NOTCH2-MIR143 being the most common fusion (73%)
    explanation: >-
      Confirms in a 93-tumor cohort that NOTCH fusions occur in the majority of
      glomus tumors, with NOTCH2-MIR143 predominating.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The common subungual GT subset lack NOTCH-gene fusions suggesting an
      alternative pathogenesis.
    explanation: >-
      Qualifies the fusion model: the classic painful subungual lesion is
      typically fusion-negative, so the NOTCH mechanism does not explain all
      glomus tumors.
  downstream:
  - target: Glomus Cell Proliferation Around Distorted Vascular Channels
    description: >-
      Deregulated NOTCH signaling in perivascular myoid cells drives clonal
      expansion of the modified smooth muscle cells of the glomus body.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23999936
      reference_title: Novel MIR143-NOTCH fusions in benign and malignant glomus tumors.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Overall NOTCH2 gene rearrangements were identified in 52% of GT,
        including all malignant cases
      explanation: >-
        The fusion is present in the majority of tumors and in every malignant
        case, consistent with it driving the proliferating tumor population.
- name: Constitutive Mitogenic Pathway Activation
  biological_scale: MOLECULAR
  role: central_effector
  description: >-
    A separate, largely fusion-independent subset of glomus tumors carries
    activating lesions of the RAS-MAPK axis. Inactivating NF1 mutations remove
    RAS-GAP restraint and produce constitutive RAS/MAPK signaling; activating
    BRAF p.Val600Glu signals independently of upstream RAS; and KRAS mutations
    occur predominantly in distal tumors while BRAF V600E is enriched in
    proximal ones. All converge on sustained MEK-ERK output, providing an
    alternative mitogenic drive to glomus cell proliferation and a rationale for
    BRAF and MEK inhibition in advanced disease.
  conforms_to: sustaining_proliferative_signaling#Constitutive Mitogenic Pathway Activation
  cell_types:
  - preferred_term: glomus cell (modified perivascular smooth muscle cell)
    term:
      id: CL:0000192
      label: smooth muscle cell
  genes:
  - preferred_term: BRAF
    term:
      id: hgnc:1097
      label: BRAF
  - preferred_term: KRAS
    term:
      id: hgnc:6407
      label: KRAS
  - preferred_term: NF1
    term:
      id: hgnc:7765
      label: NF1
  biological_processes:
  - preferred_term: MAPK cascade
    modifier: INCREASED
    term:
      id: GO:0000165
      label: MAPK cascade
  evidence:
  - reference: PMID:41693210
    reference_title: The Molecular Mechanism and Therapeutic Progress in Glomus Tumor.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Key discoveries include frequent inactivating mutations in the NF1 gene,
      leading to constitutive RAS/MAPK pathway activation, and recurrent
      "MIR143-NOTCH" gene fusions disrupting Notch signaling
    explanation: >-
      Establishes constitutive RAS/MAPK activation, alongside NOTCH fusion, as a
      recurrent oncogenic driver mechanism in glomus tumor.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      half of the GT showing NOTCH-gene fusions and a smaller subset BRAF V600E
      mutations
    explanation: >-
      Documents BRAF V600E as the alternative driver in a smaller subset of
      glomus tumors.
  - reference: PMID:40976119
    reference_title: Mutational landscape of glomus tumor and clinical application of genomic profiling based on next-generation sequencing technology.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pathway enrichment analysis revealed KRAS mutations were predominant in
      distal GT, while BRAF V600E mutations were more prevalent in proximal
      locations.
    explanation: >-
      Next-generation sequencing of 44 tumors shows anatomically stratified
      RAS-MAPK pathway lesions in glomus tumor.
  - reference: PMID:19738042
    reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      No abnormalities in NF1 or RAS mitogen-activated protein kinase activation
      were found in sporadic glomus tumors.
    explanation: >-
      A stated negative result, encoded as REFUTE rather than PARTIAL because
      that is what it is. It refutes one specific sub-claim of this node - that
      the NF1/neurofibromin route to RAS-MAPK activation operates in sporadic
      glomus tumors - while leaving the node itself standing, since the sporadic
      RAS-MAPK arm is entered through somatic BRAF V600E and KRAS
      (PMID:40976119) rather than through NF1. Read together with the NF1
      Biallelic Inactivation node, this item is what makes the syndromic and
      sporadic routes into the shared mitogenic node genuinely distinct rather
      than a single mechanism asserted twice.
  downstream:
  - target: Glomus Cell Proliferation Around Distorted Vascular Channels
    description: >-
      Sustained MEK-ERK output provides a fusion-independent proliferative drive
      in RAS-MAPK-altered glomus tumors.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:41693210
      reference_title: The Molecular Mechanism and Therapeutic Progress in Glomus Tumor.
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Key discoveries include frequent inactivating mutations in the NF1 gene,
        leading to constitutive RAS/MAPK pathway activation, and recurrent
        "MIR143-NOTCH" gene fusions disrupting Notch signaling
      explanation: >-
        Places constitutive RAS/MAPK activation among the oncogenic drivers
        "underpinning GT pathogenesis"; the review does not separately measure
        the proliferative output, so this supports the edge only indirectly.
- name: NF1 Biallelic Inactivation
  biological_scale: MOLECULAR
  role: trigger
  description: >-
    Individuals with neurofibromatosis type 1 carry a germline inactivating NF1
    variant and are predisposed to digital glomus tumors. Lesion formation
    requires somatic loss of the remaining wild-type allele; in a substantial
    minority this second hit is copy-neutral loss of heterozygosity produced by
    mitotic recombination of chromosome arm 17q rather than an intragenic
    mutation. Loss of neurofibromin, the RAS GTPase-activating protein encoded by
    NF1, removes the brake on RAS and produces RAS-MAPK hyperactivation in the
    glomus cell. Sporadic glomus tumors show no NF1 or RAS-MAPK abnormality, so
    this is a distinct, syndromic route into the same downstream mitogenic node.
  cell_types:
  - preferred_term: glomus cell (modified perivascular smooth muscle cell)
    term:
      id: CL:0000192
      label: smooth muscle cell
  genes:
  - preferred_term: NF1
    term:
      id: hgnc:7765
      label: NF1
  biological_processes:
  - preferred_term: negative regulation of Ras protein signal transduction
    modifier: DECREASED
    term:
      id: GO:0046580
      label: negative regulation of Ras protein signal transduction
  - preferred_term: Ras protein signal transduction
    modifier: INCREASED
    term:
      id: GO:0007265
      label: Ras protein signal transduction
  evidence:
  - reference: PMID:19738042
    reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Genetic analysis showed germ line and somatic NF1 mutations in seven
      tumors.
    explanation: >-
      Demonstrates the two-hit germline-plus-somatic NF1 genotype in
      NF1-associated glomus tumors.
  - reference: PMID:19738042
    reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      RAS mitogen-activated protein kinase hyperactivation was observed in
      cultured NF1(-/-) glomus cells, reflecting a lack of inhibition of the
      pathway by functional neurofibromin, the protein product of NF1.
    explanation: >-
      Functional evidence in cultured NF1-null glomus cells linking neurofibromin
      loss directly to RAS-MAPK hyperactivation.
  - reference: PMID:22250039
    reference_title: Mitotic recombination of chromosome arm 17q as a cause of loss of heterozygosity of NF1 in neurofibromatosis type 1-associated glomus tumors.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We have observed mitotic recombination in 22% of molecularly characterized
      NF1-associated glomus tumors
    explanation: >-
      Identifies mitotic recombination of 17q as a recurrent mechanism for the
      somatic second hit that reduces the germline NF1 variant to homozygosity.
  downstream:
  - target: Constitutive Mitogenic Pathway Activation
    description: >-
      Loss of neurofibromin GAP activity releases RAS, feeding the shared
      constitutive RAS-MAPK node.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:19738042
      reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        RAS mitogen-activated protein kinase hyperactivation was observed in
        cultured NF1(-/-) glomus cells, reflecting a lack of inhibition of the
        pathway by functional neurofibromin, the protein product of NF1.
      explanation: >-
        Directly demonstrates the causal step from neurofibromin loss to RAS-MAPK
        hyperactivation in glomus cells.
- name: GLMN Loss of Function with Somatic Second Hit
  biological_scale: MOLECULAR
  role: trigger
  description: >-
    Germline truncating variants in GLMN (glomulin) cause the inherited multiple
    form, glomuvenous malformation. Inheritance is autosomal dominant with
    incomplete penetrance and focal lesions, explained by a paradominant
    (Knudson two-hit) mechanism in which a somatic second hit inactivates the
    remaining wild-type allele locally; in most lesions this second hit is
    acquired uniparental isodisomy of chromosome 1p rather than an intragenic
    mutation. Glomulin normally binds the RING domain of Rbx1 and inhibits its E3
    ubiquitin ligase activity, stabilizing the substrate receptor Fbw7; its loss
    accelerates Fbw7 turnover and raises Cyclin E and c-Myc levels, releasing a
    proliferative brake in the vascular wall and leaving the smooth muscle
    compartment arrested in an incompletely differentiated, glomus-like state
    around distended venous channels.
  cell_types:
  - preferred_term: vascular smooth muscle cell
    term:
      id: CL:0000192
      label: smooth muscle cell
  genes:
  - preferred_term: GLMN
    term:
      id: hgnc:14373
      label: GLMN
  biological_processes:
  - preferred_term: protein ubiquitination
    modifier: INCREASED
    term:
      id: GO:0016567
      label: protein ubiquitination
  evidence:
  - reference: PMID:23375657
    reference_title: Somatic uniparental isodisomy explains multifocality of glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Occurrences of these mutations render the inherited glomulin variant in
      1p22.1 homozygous in the affected tissues without loss of genetic material.
      This finding demonstrates that a double hit is needed to trigger formation
      of a GVM.
    explanation: >-
      Direct demonstration of the somatic second hit (acquired uniparental
      isodisomy) required for lesion formation in glomuvenous malformation.
  - reference: PMID:15689436
    reference_title: 'Four common glomulin mutations cause two thirds of glomuvenous malformations ("familial glomangiomas"): evidence for a founder effect.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This finding suggests that GVM results from complete localised loss of
      function and explains the paradominant mode of inheritance.
    explanation: >-
      Establishes complete local loss of glomulin function as the mechanism and
      names the paradominant inheritance model.
  - reference: PMID:22405651
    reference_title: The glomuvenous malformation protein Glomulin binds Rbx1 and regulates cullin RING ligase-mediated turnover of Fbw7.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Loss of Glmn in a variety of cells, tissues, and GVM lesions results in
      decreased levels of Fbw7 and increased levels of Cyclin E and c-Myc.
    explanation: >-
      Provides the molecular consequence of glomulin loss, linking it to
      stabilization of the proliferative effectors Cyclin E and c-Myc.
  downstream:
  - target: Glomus Cell Proliferation Around Distorted Vascular Channels
    description: >-
      Biallelic glomulin inactivation blocks terminal vascular smooth muscle
      differentiation and de-represses Cyclin E/c-Myc, yielding multifocal
      glomus-cell-lined venous channels.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:22405651
      reference_title: The glomuvenous malformation protein Glomulin binds Rbx1 and regulates cullin RING ligase-mediated turnover of Fbw7.
      supports: PARTIAL
      evidence_source: IN_VITRO
      snippet: >-
        Loss of Glmn in a variety of cells, tissues, and GVM lesions results in
        decreased levels of Fbw7 and increased levels of Cyclin E and c-Myc.
      explanation: >-
        Supplies the molecular link from glomulin loss to de-repression of the
        proliferative effectors Cyclin E and c-Myc, including in GVM lesions
        themselves; the proliferative phenotype of the lesional glomus cells is
        inferred rather than directly measured, hence PARTIAL.
  - target: Venous Malformation
    description: >-
      Loss of glomulin produces the distended, poorly muscularized venous
      channels that give glomuvenous malformations their compressible,
      blue-purple appearance.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:15689436
      reference_title: 'Four common glomulin mutations cause two thirds of glomuvenous malformations ("familial glomangiomas"): evidence for a founder effect.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Glomuvenous malformation (GVM) ("familial glomangioma") is a localised
        cutaneous vascular lesion histologically characterised by abnormal smooth
        muscle-like "glomus cells" in the walls of distended endothelium lined
        channels.
      explanation: >-
        Links GLMN-associated disease directly to the distended,
        glomus-cell-walled venous channels that constitute the malformation.
- name: Glomus Cell Proliferation Around Distorted Vascular Channels
  biological_scale: CELLULAR
  role: central_effector
  description: >-
    Whichever driver lesion is present, the tumor is formed by clonal expansion
    of glomus cells, the modified perivascular smooth muscle cells of the
    thermoregulatory glomus body. Immunohistochemical expression of smoothelin
    confirms that these cells are genuinely contractile smooth muscle cells. The
    proliferating cells form solid nests and concentric cuffs around branching,
    ectatic vascular spaces, replacing the normal Sucquet-Hoyer canal
    architecture of the arteriovenous anastomosis, and deposit a continuous
    pericellular type IV collagen basement membrane that reflects their retained
    myoid phenotype.
  cell_types:
  - preferred_term: glomus cell (modified perivascular smooth muscle cell)
    term:
      id: CL:0000192
      label: smooth muscle cell
  - preferred_term: pericyte
    term:
      id: CL:0000669
      label: pericyte
  biological_processes:
  - preferred_term: smooth muscle cell proliferation
    modifier: INCREASED
    term:
      id: GO:0048659
      label: smooth muscle cell proliferation
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
  notes: >-
    Known split candidate, deliberately deferred. This node carries two claims
    at two scales: a CELLULAR clonal-expansion claim (glomus cells proliferate)
    and a TISSUE-scale architectural claim (they form concentric cuffs around
    ectatic channels, replace the Sucquet-Hoyer canal, and deposit pericellular
    type IV collagen). Per CLAUDE.md, two competing biological_scale values are
    the canonical bundling signal, and the correct fix is to split this into an
    atomic proliferation node and an atomic perivascular-architecture node.
    That is not done here because this node is the convergence point of all four
    driver arms and the target of the excision treatment: splitting it would
    re-target four incoming edges, four outgoing edges and one target_mechanisms
    reference mid-review. biological_scale is set to CELLULAR on the leading
    claim and the split is left as a follow-up.
  evidence:
  - reference: PMID:41693210
    reference_title: The Molecular Mechanism and Therapeutic Progress in Glomus Tumor.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumor (GT) is a rare mesenchymal neoplasm presumed to originate from
      the neuromyoarterial glomus body.
    explanation: >-
      Establishes the neuromyoarterial glomus body as the cell of origin for the
      proliferating tumor population.
  - reference: PMID:27184662
    reference_title: Smoothelin and WT-1 expression in glomus tumors and glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Smoothelin expression in glomic cells indicates that they are contractile
      smooth muscle cells
    explanation: >-
      Immunohistochemical confirmation that the proliferating glomus cells are
      contractile smooth muscle cells, the basis of their myoid phenotype.
  downstream:
  - target: Nociceptor-Rich and Mast-Cell-Rich Tumor Stroma
    description: >-
      The expanding glomus tumor is densely invested by unmyelinated sensory
      nerve fibers and by stromal mast cells.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:93364
      reference_title: 'Mast cells in solitary glomus tumors: a possible algogenic role.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Electron microscopy revealed various types and degrees of degranulation
        of mast cell granules, and also disclosed a close correlation between
        mast cells and non-myelinated nerve fibers.
      explanation: >-
        Demonstrates that the tumor tissue itself contains the mast cell and
        unmyelinated nerve fiber population that constitutes this stroma.
  - target: Loss of Thermoregulatory Shunt Function
    description: >-
      Replacement of the normal Sucquet-Hoyer canal disrupts the
      thermoregulatory arteriovenous shunt formed by the glomus body.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:39392364
      reference_title: Complete response to encorafenib plus binimetinib in a BRAF V600E-mutant metastasic malignant glomus tumor.
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Glomus tumors (GT) are very rare mesenchymal neoplasms arising from
        glomus bodies, arteriovenous structures located in the dermis and
        involved in thermoregulation.
      explanation: >-
        Establishes that the structure the tumor arises from and replaces is the
        thermoregulatory arteriovenous glomus body; the functional loss itself is
        inferred, hence PARTIAL.
  - target: Malignant Transformation
    description: >-
      A small minority of glomus tumors acquire deep location, large size,
      atypical mitoses, and nuclear atypia, defining malignant glomus tumor.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:11145243
      reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Atypical features were usually observed centrally with a rim of
        benign-appearing glomus tumor.
      explanation: >-
        Morphologic evidence that the atypical/malignant population arises within
        a pre-existing conventional glomus tumor, supporting progression from the
        benign proliferation rather than a separate origin.
  - target: Subungual Nodule
    description: >-
      The expanding cellular mass presents as a small, often bluish subungual or
      dermal nodule.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:34239958
      reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        There were 14 patients (82.35%) with subungual tumors
      explanation: >-
        Documents that the proliferating tumor most often presents as a
        subungual mass.
  - target: Gastric (Visceral) Glomus Tumor
    description: >-
      The same proliferating glomus cell population arising in the gastric wall
      rather than at an acral site presents as a submucosal antral mass. Because
      the visceral lesion is histologically and immunophenotypically the same
      entity as the soft tissue one, this node is its proximate cause too; only
      the anatomic site, and therefore the clinical presentation, differs.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:24817939
      reference_title: 'Features of gastric glomus tumor: a clinicopathologic, immunohistochemical and molecular retrospective study.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Our results show that GTs in the stomach are histologically and
        immunophenotypically fully comparable with the glomus tumors of
        peripheral soft tissues.
      explanation: >-
        Establishes that the gastric lesion is produced by the same glomus cell
        proliferation modelled in this node, which is what licenses the causal
        edge rather than treating the visceral presentation as a separate
        process.
    - reference: PMID:32337257
      reference_title: 'Gastric Glomus Tumor: A Clinicopathologic and Immunohistochemical Study of 21 Cases.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Microscopically, small, round cell nodules surrounded the expansion of
        blood vessels in a nest pattern.
      explanation: >-
        Confirms that the gastric lesion shows the same nested, perivascular
        glomus cell architecture this node describes, at the gastric site.
- name: Nociceptor-Rich and Mast-Cell-Rich Tumor Stroma
  biological_scale: TISSUE
  role: mediator
  description: >-
    Glomus tumors are unusually densely innervated: numerous unmyelinated
    nociceptive nerve fibers ramify among the tumor cells, and the stroma
    contains abundant mast cells that show ultrastructural evidence of
    degranulation in close apposition to those fibers. Release of histamine and
    other algogenic granule contents onto adjacent nociceptors, together with
    pressure transmitted by contraction of the smooth-muscle-like tumor cells
    within a confined subungual compartment, accounts for the disproportionate
    severity of pain relative to lesion size.
  cell_types:
  - preferred_term: mast cell
    term:
      id: CL:0000097
      label: mast cell
  biological_processes:
  - preferred_term: sensory perception of pain
    modifier: INCREASED
    term:
      id: GO:0019233
      label: sensory perception of pain
  - preferred_term: mast cell degranulation
    modifier: INCREASED
    term:
      id: GO:0043303
      label: mast cell degranulation
  evidence:
  - reference: PMID:93364
    reference_title: 'Mast cells in solitary glomus tumors: a possible algogenic role.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Electron microscopy revealed various types and degrees of degranulation of
      mast cell granules, and also disclosed a close correlation between mast
      cells and non-myelinated nerve fibers.
    explanation: >-
      Ultrastructural demonstration of degranulating mast cells apposed to
      unmyelinated nerve fibers within the glomus tumor stroma.
  - reference: PMID:93364
    reference_title: 'Mast cells in solitary glomus tumors: a possible algogenic role.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These findings suggest that mast cells may play an algogenic role in
      solitary glomus tumors
    explanation: >-
      Proposes mast cell mediator release as the algogenic mechanism underlying
      glomus tumor pain.
  downstream:
  - target: Severe Paroxysmal Pain
    description: >-
      Activation of the dense intratumoral nociceptor population produces
      lancinating, paroxysmal pain out of proportion to lesion size.
    evidence:
    - reference: PMID:93364
      reference_title: 'Mast cells in solitary glomus tumors: a possible algogenic role.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        These findings suggest that mast cells may play an algogenic role in
        solitary glomus tumors
      explanation: >-
        Attributes the pain of glomus tumor to algogenic mediator release within
        the tumor stroma.
  - target: Pinpoint Tenderness
    description: >-
      Focal mechanical stimulation of the innervated nodule reproduces the pain,
      the basis of the Love pin test.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:34239958
      reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The Love’s pin test is used to confirm the exquisite point tenderness. A
        pinhead is used to apply gentle localized pressure to the tender area as
        pointed out by the patient subjectively. This typically elicits intense
        tenderness.
      explanation: >-
        Describes the mechanical provocation of focal tenderness over the lesion,
        the clinical readout of this edge.
- name: Loss of Thermoregulatory Shunt Function
  biological_scale: TISSUE
  role: consequence
  description: >-
    The normal glomus body is an arteriovenous anastomosis in the dermis whose
    smooth muscle tone shunts blood away from the capillary bed during cold
    exposure. Tumor-induced distortion of this structure, combined with
    cold-evoked contraction of the tumor's smooth-muscle-like cells and
    sensitization of the surrounding nociceptors, converts a normally innocuous
    cold stimulus into a painful one.
  biological_processes:
  - preferred_term: temperature homeostasis
    modifier: ABNORMAL
    term:
      id: GO:0001659
      label: temperature homeostasis
  evidence:
  - reference: PMID:39392364
    reference_title: Complete response to encorafenib plus binimetinib in a BRAF V600E-mutant metastasic malignant glomus tumor.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumors (GT) are very rare mesenchymal neoplasms arising from glomus
      bodies, arteriovenous structures located in the dermis and involved in
      thermoregulation.
    explanation: >-
      Establishes the thermoregulatory arteriovenous glomus body as the
      structure from which the tumor arises and whose function it disrupts.
  - reference: PMID:19738042
    reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumors are small, benign but painful tumors that originate from the
      glomus body, a thermoregulatory shunt concentrated in the fingers and toes.
    explanation: >-
      Independently identifies the glomus body as a thermoregulatory shunt
      concentrated at the digits, linking tumor site to the disrupted function.
  downstream:
  - target: Cold Hypersensitivity
    description: >-
      Cold exposure of the affected digit provokes intense pain, the second
      element of the classic glomus tumor triad.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:34239958
      reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Cold intolerance is tested by local application of an ice cube to the
        affected area.
      explanation: >-
        Documents cold-provoked pain as a reproducible clinical feature of the
        lesion, the observable consequence of the disrupted thermoregulatory
        shunt.
- name: Malignant Transformation
  biological_scale: TISSUE
  role: outcome
  description: >-
    Malignant glomus tumor (glomangiosarcoma) is rare and is defined
    morphologically rather than molecularly: deep anatomic location together with
    size greater than 2 cm, the presence of atypical mitotic figures, or
    moderate-to-high nuclear grade with at least 5 mitotic figures per 50
    high-power fields. Deep location, size above 2 cm, and atypical mitoses are
    each independently associated with metastatic risk, whereas high nuclear
    grade alone (symplastic glomus tumor) is not.
  biological_processes:
  - preferred_term: cell population proliferation
    modifier: INCREASED
    term:
      id: GO:0008283
      label: cell population proliferation
  evidence:
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Five-year cumulative metastatic risk increased significantly for tumors
      with a deep location (p = 0.005), with a size of more than 2 cm (p =
      0.004), and with atypical mitotic figures (p = 0.004).
    explanation: >-
      Identifies the three features that independently predict metastasis and
      therefore define malignancy in glomus tumor.
  downstream:
  - target: Metastasis
    description: >-
      Glomus tumors meeting the malignancy criteria metastasize in a substantial
      minority of cases.
    evidence:
    - reference: PMID:11145243
      reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        metastasis was observed in 38% of tumors fulfilling the criteria for
        malignancy
      explanation: >-
        Quantifies the metastatic outcome of tumors meeting the malignancy
        criteria.
phenotypes:
- category: Clinical
  name: Severe Paroxysmal Pain
  description: >-
    Lancinating, paroxysmal pain radiating from the lesion, characteristically
    far out of proportion to its small size, and a component of the classic
    diagnostic triad.
  phenotype_term:
    preferred_term: Pain
    term:
      id: HP:0012531
      label: Pain
    temporality: RECURRENT
    severity: SEVERE
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These tumours usually present as a bluish or pinkish red discolouration of
      the nail plate with classical triad of localised tenderness, severe pain,
      and cold sensitivity.
    explanation: >-
      Names severe pain as one of the three classical presenting features of
      glomus tumor.
- category: Clinical
  name: Cold Hypersensitivity
  description: >-
    Exposure of the affected digit to cold reliably provokes intense pain, a
    normally innocuous stimulus becoming painful. This underlies the diagnostic
    cold sensitivity (Hildreth ice-water) test. It is the least consistently
    present element of the triad.
  phenotype_term:
    preferred_term: Cold-induced allodynia
    term:
      id: HP:0012533
      label: Allodynia
  frequency: FREQUENT
  evidence:
  - reference: PMID:42181359
    reference_title: 'Diagnostic Delay and Clinical Characteristics of Glomus Tumors in the Hand: A Case Series of 11 Patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Localized point tenderness was observed in 10 patients (91%), whereas cold
      hypersensitivity was present in four patients (36%), and the complete
      symptom triad was observed in four patients (36%).
    explanation: >-
      Quantifies cold hypersensitivity in 36% of a consecutive hand glomus tumor
      series, supporting the FREQUENT (30-79%) frequency band.
- category: Clinical
  name: Pinpoint Tenderness
  description: >-
    Focal pressure over the lesion, classically with a pin head, reproduces the
    pain precisely at a single point (the Love pin test), while surrounding skin
    is unaffected. This is the most consistently present element of the triad.
  phenotype_term:
    preferred_term: Focal pinpoint tenderness (positive Love pin test)
    term:
      id: HP:0012531
      label: Pain
  frequency: VERY_FREQUENT
  notes: >-
    Ontology gap - term request needed. This phenotype and "Severe Paroxysmal
    Pain" both fall back to HP:0012531 Pain, which loses the clinically
    distinctive feature: point tenderness is the Love pin-test finding and the
    most sensitive element of the triad, whereas the paroxysmal pain is
    spontaneous and lancinating. HPO offers no usable alternative. HP:0025283
    "Tender" is_a HP:0025280 Pain characteristic, i.e. it sits on the modifier
    branch rather than under HP:0000118 Phenotypic abnormality, so it cannot
    serve as a phenotype_term; every other HPO tenderness term is specific to a
    body site other than the digit (HP:0020226 Nipple tenderness, HP:0100809
    Scalp tenderness, HP:6000106 Costovertebral angle tenderness, HP:6000107
    Cervical motion tenderness, HP:6001407 Peroneal tendon tenderness). The two
    phenotypes are therefore held apart by preferred_term until a
    localized/pinpoint tenderness HPO term exists.
  evidence:
  - reference: PMID:42181359
    reference_title: 'Diagnostic Delay and Clinical Characteristics of Glomus Tumors in the Hand: A Case Series of 11 Patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Localized point tenderness was observed in 10 patients (91%), whereas cold
      hypersensitivity was present in four patients (36%), and the complete
      symptom triad was observed in four patients (36%).
    explanation: >-
      Documents localized point tenderness in 91% of patients, supporting the
      VERY_FREQUENT (80-100%) frequency band.
- category: Clinical
  name: Subungual Nodule
  description: >-
    A small, often bluish or reddish nodule beneath the nail plate, frequently
    with secondary nail-plate discoloration or deformity. Extra-digital cutaneous
    and deep soft tissue sites also occur but are less common.
  phenotype_term:
    preferred_term: Skin nodule
    term:
      id: HP:0200036
      label: Skin nodule
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There were 14 patients (82.35%) with subungual tumors
    explanation: >-
      Documents subungual location in 82% of a hand glomus tumor case series.
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These tumours usually present as a bluish or pinkish red discolouration of
      the nail plate
    explanation: >-
      Describes the characteristic bluish subungual appearance of the lesion.
- category: Clinical
  name: Gastric (Visceral) Glomus Tumor
  description: >-
    Glomus tumor is not a cutaneous-only disease. Beyond the acral and subungual
    sites that dominate clinical practice, tumors arise at deep soft tissue and
    visceral sites, most characteristically in the gastric wall, where the
    antrum is the commonest location. Gastric lesions present as a submucosal
    mass found at endoscopy or on cross-sectional imaging, or with upper
    gastrointestinal bleeding, and are routinely mistaken preoperatively for
    gastrointestinal stromal tumor. They are the same entity as the soft tissue
    lesion - histologically and immunophenotypically comparable, actin- and type
    IV collagen-positive, and negative for the KIT/PDGFRA mutations of GIST -
    are almost always benign, and are cured by complete local resection. They do
    not produce the paroxysmal-pain and cold-sensitivity triad, which depends on
    the dense acral innervation modelled in the nociceptor-rich stroma node.
  phenotype_term:
    preferred_term: Neoplasm of the stomach
    term:
      id: HP:0006753
      label: Neoplasm of the stomach
  evidence:
  - reference: PMID:32337257
    reference_title: 'Gastric Glomus Tumor: A Clinicopathologic and Immunohistochemical Study of 21 Cases.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common location was the antrum, the mean age of patients was 49.3
      years, and the mean tumor size was 2.1 cm.
    explanation: >-
      Establishes the gastric antrum as the characteristic visceral site in a
      21-case surgical series.
  - reference: PMID:32337257
    reference_title: 'Gastric Glomus Tumor: A Clinicopathologic and Immunohistochemical Study of 21 Cases.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The majority of GGTs are benign, and local surgery achieving complete
      resection is the most effective treatment method.
    explanation: >-
      Establishes the benign behaviour and surgical management of the gastric
      presentation, mirroring the acral lesion.
  - reference: PMID:24817939
    reference_title: 'Features of gastric glomus tumor: a clinicopathologic, immunohistochemical and molecular retrospective study.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our results show that GTs in the stomach are histologically and
      immunophenotypically fully comparable with the glomus tumors of peripheral
      soft tissues.
    explanation: >-
      Confirms that the gastric lesion is the same entity as the soft tissue
      glomus tumor rather than a separate, similarly named tumor - the point
      that justifies curating it inside this entry.
  - reference: PMID:24817939
    reference_title: 'Features of gastric glomus tumor: a clinicopathologic, immunohistochemical and molecular retrospective study.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      No C-kit or PDGFR-alpha genetic mutations were detected in all patients.
    explanation: >-
      Supplies the molecular discriminator from gastrointestinal stromal tumor,
      the diagnosis gastric glomus tumors are usually mistaken for.
  notes: >-
    No frequency band is asserted. The visceral share of all glomus tumors
    cannot be estimated from the available literature, which consists of
    single-institution surgical-pathology series (11 and 21 cases) with no
    common denominator; a numeric or banded frequency here would be fabricated.
- category: Clinical
  name: Venous Malformation
  description: >-
    In glomuvenous malformation, multiple compressible blue-purple nodules or
    plaques composed of distended, endothelium-lined channels whose walls contain
    abnormal glomus cells.
  subtype: Glomuvenous Malformation
  phenotype_term:
    preferred_term: Venous malformation
    term:
      id: HP:0012721
      label: Venous malformation
  evidence:
  - reference: PMID:15689436
    reference_title: 'Four common glomulin mutations cause two thirds of glomuvenous malformations ("familial glomangiomas"): evidence for a founder effect.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomuvenous malformation (GVM) ("familial glomangioma") is a localised
      cutaneous vascular lesion histologically characterised by abnormal smooth
      muscle-like "glomus cells" in the walls of distended endothelium lined
      channels.
    explanation: >-
      Describes the venous-malformation morphology of the inherited multiple
      form.
- category: Clinical
  name: Metastasis
  description: >-
    Distant spread, seen only in glomus tumors meeting the histologic criteria
    for malignancy, most often to lung and bone.
  subtype: Malignant Glomus Tumor
  phenotype_term:
    preferred_term: Distant metastasis
    term:
      id: HP:0002664
      label: Neoplasm
  notes: >-
    Ontology gap - term request needed. HP:0002664 Neoplasm is uninformative
    inside a neoplasm entry, but HPO has no generic metastasis term: a search of
    HPO for "metasta" returns exactly one class, HP:0200059 Metastatic
    angiosarcoma, which is a different disease. The intended meaning (distant
    metastatic spread, most often to lung and bone) is therefore carried by
    preferred_term and by the description until HPO gains a generic
    "Metastasis" phenotype.
  evidence:
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      metastasis was observed in 38% of tumors fulfilling the criteria for
      malignancy
    explanation: >-
      Quantifies metastatic risk restricted to tumors that meet the malignancy
      criteria.
histopathology:
- name: Concentric Perivascular Glomus Cell Arrangement
  finding_term:
    preferred_term: Concentric Perivascular Arrangement of Tumor Cells
    term:
      id: NCIT:C51140
      label: Concentric Perivascular Arrangement of Tumor Cells
  diagnostic: true
  description: >-
    Uniform, small round glomus cells with central "punched-out" nuclei and
    sharply defined cell borders arranged in concentric cuffs around
    capillary-sized vascular channels, recapitulating the modified smooth muscle
    of the Sucquet-Hoyer canal.
  evidence:
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the cases showed typical features of monomorphic epithelioid to cuboidal
      cells arranged in solid pattern and encuffing the thin-walled blood vessels
    explanation: >-
      Describes the defining perivascular cuffing of uniform glomus cells around
      thin-walled vessels in a 93-tumor cohort.
- name: Nested Growth Pattern
  finding_term:
    preferred_term: Nested Pattern
    term:
      id: NCIT:C35892
      label: Nested Pattern
  description: >-
    Solid nests and sheets of glomus cells separated by a delicate,
    collagen-rich, mast-cell-containing stroma; the predominant architecture of
    the solid glomus tumor variant.
  evidence:
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the cases showed typical features of monomorphic epithelioid to cuboidal
      cells arranged in solid pattern and encuffing the thin-walled blood vessels
    explanation: >-
      Documents the solid/nested architecture as the typical growth pattern of
      conventional glomus tumor.
  - reference: PMID:93364
    reference_title: 'Mast cells in solitary glomus tumors: a possible algogenic role.'
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Electron microscopy revealed various types and degrees of degranulation of
      mast cell granules, and also disclosed a close correlation between mast
      cells and non-myelinated nerve fibers.
    explanation: >-
      Confirms the mast-cell content of the intervening stroma described here; it
      does not address the nested architecture itself, hence PARTIAL.
- name: Atypical Mitotic Figures
  finding_term:
    preferred_term: Atypical Mitotic Figures
    term:
      id: NCIT:C35962
      label: Atypical Mitotic Figures
  description: >-
    Atypical mitoses are one of the three independent morphologic predictors of
    metastasis and are a defining criterion for malignant glomus tumor.
  evidence:
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Five-year cumulative metastatic risk increased significantly for tumors
      with a deep location (p = 0.005), with a size of more than 2 cm (p =
      0.004), and with atypical mitotic figures (p = 0.004).
    explanation: >-
      Establishes atypical mitotic figures as an independent predictor of
      metastasis in glomus tumor.
biochemical:
- name: Smooth Muscle Actin Expression
  biomarker_term:
    preferred_term: Actin, Aortic Smooth Muscle
    term:
      id: NCIT:C103972
      label: Actin, Aortic Smooth Muscle
  notes: >-
    Diffuse cytoplasmic smooth muscle (muscle-specific) actin positivity is the
    single most consistent immunophenotypic feature of glomus tumor and reflects
    its modified smooth muscle lineage. It is typically accompanied by
    h-caldesmon positivity and a continuous pericellular type IV collagen
    basement membrane.
  evidence:
  - reference: PMID:1848411
    reference_title: 'Cutaneous glomus tumor. A comparative immunohistochemical study with pseudoangiomatous intradermal melanocytic nevi.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      all tumors were immunoreactive for muscle-specific actin, but only two
      expressed desmin
    explanation: >-
      Documents uniform muscle-specific actin positivity with only variable
      desmin expression, the characteristic glomus tumor immunophenotype.
- name: Desmin Expression
  biomarker_term:
    preferred_term: Desmin
    term:
      id: NCIT:C96450
      label: Desmin
  notes: >-
    Desmin is characteristically negative or only focally and inconsistently
    expressed in glomus tumor, in contrast to true smooth muscle tumors such as
    leiomyoma and leiomyosarcoma, and is therefore useful in differential
    diagnosis.
  evidence:
  - reference: PMID:1848411
    reference_title: 'Cutaneous glomus tumor. A comparative immunohistochemical study with pseudoangiomatous intradermal melanocytic nevi.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      all tumors were immunoreactive for muscle-specific actin, but only two
      expressed desmin
    explanation: >-
      Shows desmin expression in only 2 of 6 glomus tumors, supporting its
      variable-to-negative status.
- name: Contractile Smooth Muscle Marker Expression (Smoothelin and h-Caldesmon)
  biomarker_term:
    preferred_term: Caldesmon
    term:
      id: NCIT:C113326
      label: Caldesmon
  notes: >-
    Glomus cells express the contractile-smooth-muscle markers smoothelin and
    h-caldesmon, confirming that they are genuinely contractile smooth muscle
    cells rather than undifferentiated perivascular cells. NCIT lacks a
    smoothelin concept, so this readout is anchored on caldesmon, the companion
    contractile marker in the same diagnostic panel.
  evidence:
  - reference: PMID:27184662
    reference_title: Smoothelin and WT-1 expression in glomus tumors and glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Smoothelin expression in glomic cells indicates that they are contractile
      smooth muscle cells
    explanation: >-
      Immunohistochemical panel including h-caldesmon establishes the contractile
      smooth muscle phenotype of glomus cells.
diagnosis:
- name: Clinical provocation triad (Love's pin test, Hildreth's test, cold test)
  description: >-
    Three bedside provocation manoeuvres localise a suspected glomus tumor.
    Love's pin test applies focal pressure with a pinhead over the point the
    patient indicates and reproduces exquisite tenderness. Hildreth's test
    repeats Love's test under tourniquet-induced arm ischaemia: the tenderness
    abates and returns sharply when the tourniquet is released, which is what
    makes it specific. The cold test applies an ice cube to the lesion to
    reproduce cold-provoked pain. Trans-illumination of the fingertip in a dark
    room may show the lesion. These manoeuvres localise disease but do not
    replace histopathology.
  diagnosis_term:
    preferred_term: physical examination
    term:
      id: NCIT:C20989
      label: Physical Examination
  evidence:
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In the Hildreth’s test, transient ischemia is produced at the arm’s level
      with application of a tourniquet. With the ischemia in place, when the
      Love’s pin test is repeated, there is absence of the tenderness of previous
      magnitude. Upon removal of the tourniquet, there is sharp return of the
      bothering pain.
    explanation: >-
      Defines the Hildreth manoeuvre and its relationship to Love's pin test.
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The cold sensitivity test is reported to have 100% sensitivity,
      specificity and diagnostic accuracy. The Love’s test has 100% sensitivity
      and 78% diagnostic accuracy, whereas the Hildreth’s test has 71.4%
      sensitivity, 100% specificity and 78% diagnostic accuracy.
    explanation: >-
      Gives the reported operating characteristics of each manoeuvre; note these
      are single-series figures from a small cohort, not pooled estimates.
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The frequency of various presenting clinical findings was as follows: Pain
      (n=17; 100%), tenderness (n=17; 100%), cold sensitivity (n=13; 76.47%),
      visible tumor (n=4; 23.52%), nail changes (n=2; 11.76%), Love’s pin test
      (n=17; 100%), Cold sensitivity test (n=17; 100%) Hildreth’s test (n=12;
      70.58%), and trans-illumination test (n=9; 52.94%).
    explanation: >-
      Quantifies the yield of each manoeuvre in a consecutive hand glomus tumor
      series.
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In addition to the different clinical tests including Love's pin test,
      Hildreth's test, and trans-illumination test, imaging studies such as
      magnetic resonance imaging (MRI), ultrasonography, and radiography are
      often helpful in the diagnosis.
    explanation: >-
      Independent review naming the same three clinical tests as the standard
      bedside work-up.
- name: Contrast-enhanced high-resolution MRI
  description: >-
    Gadolinium-enhanced high-resolution MRI is the preferred imaging study for a
    suspected subungual glomus tumor. The lesion is characteristically low
    signal on T1-weighted and markedly hyperintense on T2-weighted images with
    avid enhancement, and lesions as small as 2 mm can be detected. It also
    identifies additional asymptomatic lesions (which would raise the question of
    NF1 or glomuvenous malformation) and helps exclude alternative diagnoses.
  diagnosis_term:
    preferred_term: magnetic resonance imaging
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  evidence:
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It is currently considered the gold standard diagnostic investigation. It
      is non-invasive and doesn’t involve any exposure to radiation. It can
      detect early lesions as small as 2 mm.
    explanation: >-
      States the role and resolution of high-resolution contrast MRI in this
      diagnosis.
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Characteristically there is low-signal intensity on T1-weighted images
      whereas marked hyperintensity on T2-weighted images
    explanation: >-
      Gives the characteristic MRI signal signature of the lesion.
- name: Ultrasonography
  description: >-
    High-resolution ultrasound is a cheap, accessible first-line adjunct that
    may show a small hypoechoic, hypervascular nodule, sometimes with scalloping
    of the underlying distal phalanx. It is less sensitive than MRI for very
    small lesions.
  diagnosis_term:
    preferred_term: ultrasound imaging
    term:
      id: NCIT:C17230
      label: Ultrasound Imaging
  evidence:
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      imaging studies such as magnetic resonance imaging (MRI), ultrasonography,
      and radiography are often helpful in the diagnosis.
    explanation: >-
      Names ultrasonography among the helpful imaging modalities; the review does
      not report its operating characteristics, hence PARTIAL.
- name: Histopathologic examination with immunohistochemistry
  description: >-
    Definitive diagnosis is histopathologic. Sheets and perivascular cuffs of
    monomorphic, sharply bordered glomus cells are confirmed by an
    immunohistochemical panel showing diffuse smooth muscle actin, smoothelin and
    h-caldesmon positivity with pericellular type IV collagen, and negativity for
    S100/SOX10, cytokeratin and endothelial markers in the tumor cells. Desmin is
    variable. The same specimen is graded against the Folpe criteria to assign
    benign, symplastic, uncertain-malignant-potential or malignant category.
  diagnosis_term:
    preferred_term: histopathologic examination with immunohistochemistry
    term:
      id: NCIT:C16853
      label: Microscopy
  notes: >-
    NCIT:C16722 (Immunohistochemistry) is the semantically exact term but is not
    reachable from NCIT:C25218 (Clinical Intervention or Procedure), the root of
    the TreatmentActionTerm dynamic enum, so it fails term validation here.
    Microscopy is the nearest reachable ancestor; the specific procedure is
    carried by preferred_term.
  evidence:
  - reference: PMID:1848411
    reference_title: 'Cutaneous glomus tumor. A comparative immunohistochemical study with pseudoangiomatous intradermal melanocytic nevi.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      all tumors were immunoreactive for muscle-specific actin, but only two
      expressed desmin
    explanation: >-
      Establishes the diagnostic actin-positive, desmin-variable immunophenotype.
  - reference: PMID:27184662
    reference_title: Smoothelin and WT-1 expression in glomus tumors and glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Smoothelin expression in glomic cells indicates that they are contractile
      smooth muscle cells
    explanation: >-
      Adds smoothelin to the confirmatory contractile-smooth-muscle panel.
  - reference: PMID:11145243
    reference_title: 'Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They evaluated size, depth, growth pattern, cellularity, nuclear grade,
      number of mitotic figures per 50 high-power fields (HPF), atypical mitotic
      figures, vascular space involvement, and necrosis to define criteria for
      malignancy in glomus tumors.
    explanation: >-
      Lists the histologic parameters that must be assessed on the excision
      specimen to assign the Folpe malignancy category.
- name: NOTCH fusion / BRAF molecular testing
  description: >-
    FISH break-apart or RNA-based fusion testing for NOTCH1/NOTCH2/NOTCH3
    rearrangement, and BRAF V600E testing (by sequencing or VE1
    immunohistochemistry), are reserved for deep, visceral, atypical, malignant
    or diagnostically ambiguous lesions. A NOTCH rearrangement supports glomus
    tumor over the PDGFRB-mutant myofibroma/myopericytoma arm of the pericytic
    family; a BRAF V600E result is directly actionable in metastatic disease.
    Molecular testing is NOT required for a classic subungual lesion, which is
    typically fusion-negative in any case.
  diagnosis_term:
    preferred_term: fluorescence in situ hybridization
    term:
      id: NCIT:C17563
      label: Fluorescence In Situ Hybridization
  evidence:
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      rearrangements of NOTCH genes are seen in over half of GT, with
      NOTCH2-MIR143 being the most common fusion (73%)
    explanation: >-
      Establishes the diagnostic yield of NOTCH rearrangement testing in glomus
      tumor.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The common subungual GT subset lack NOTCH-gene fusions suggesting an
      alternative pathogenesis.
    explanation: >-
      Explains why a negative fusion result in a classic subungual lesion does
      not exclude the diagnosis.
  - reference: PMID:40976119
    reference_title: Mutational landscape of glomus tumor and clinical application of genomic profiling based on next-generation sequencing technology.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pathway enrichment analysis revealed KRAS mutations were predominant in
      distal GT, while BRAF V600E mutations were more prevalent in proximal
      locations.
    explanation: >-
      Supports next-generation sequencing as the route to the actionable RAS-MAPK
      lesions.
genetic:
- name: MIR143-NOTCH2 fusion
  gene_term:
    preferred_term: NOTCH2
    term:
      id: hgnc:7882
      label: NOTCH2
  variant_origin: SOMATIC
  notes: >-
    The recurrent fusion of MIR143 (hgnc:31530) to a NOTCH gene family member is
    the characteristic somatic driver of glomus tumor. NOTCH2 is the most
    frequent partner (73% of fusions), with NOTCH1 (hgnc:7881) and NOTCH3
    (hgnc:7883) also reported. Fusions are absent from most subungual tumors.
  evidence:
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      rearrangements of NOTCH genes are seen in over half of GT, with
      NOTCH2-MIR143 being the most common fusion (73%)
    explanation: >-
      Establishes NOTCH2-MIR143 as the predominant fusion in a large glomus tumor
      cohort.
- name: MIR143-NOTCH3 fusion
  gene_term:
    preferred_term: NOTCH3
    term:
      id: hgnc:7883
      label: NOTCH3
  variant_origin: SOMATIC
  notes: >-
    A minority of benign soft tissue glomus tumors carry NOTCH3 rearrangement,
    consistent with the shared role of NOTCH2 and NOTCH3 in vascular smooth
    muscle development.
  evidence:
  - reference: PMID:23999936
    reference_title: Novel MIR143-NOTCH fusions in benign and malignant glomus tumors.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NOTCH3 rearrangements were identified in 9% of GTs, all present in benign
      soft tissue GT, one case being fused to MIR143
    explanation: >-
      Documents NOTCH3 as a less frequent fusion partner restricted to benign
      soft tissue tumors.
- name: BRAF V600E
  gene_term:
    preferred_term: BRAF
    term:
      id: hgnc:1097
      label: BRAF
  variant_origin: SOMATIC
  notes: >-
    Activating BRAF p.Val600Glu occurs in a subset of glomus tumors, largely
    distinct from NOTCH-fusion-positive tumors, and is enriched in proximally
    located lesions. It is a validated therapeutic target in metastatic disease.
  evidence:
  - reference: PMID:40976119
    reference_title: Mutational landscape of glomus tumor and clinical application of genomic profiling based on next-generation sequencing technology.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pathway enrichment analysis revealed KRAS mutations were predominant in
      distal GT, while BRAF V600E mutations were more prevalent in proximal
      locations.
    explanation: >-
      Documents BRAF V600E in glomus tumor and its anatomic enrichment.
- name: KRAS
  gene_term:
    preferred_term: KRAS
    term:
      id: hgnc:6407
      label: KRAS
  variant_origin: SOMATIC
  notes: >-
    Activating KRAS mutation is the RAS-level counterpart of BRAF V600E within
    the RAS-MAPK arm of glomus tumor, and the two show a reciprocal anatomic
    distribution: in next-generation sequencing of glomus tumors, KRAS lesions
    were enriched in distally located tumors whereas BRAF V600E predominated in
    proximal ones. KRAS-mutant tumors therefore have no mutant BRAF kinase to
    inhibit, and the actionable node for them is MEK downstream of RAS, the same
    rationale used for the NF1-deficient arm.
  evidence:
  - reference: PMID:40976119
    reference_title: Mutational landscape of glomus tumor and clinical application of genomic profiling based on next-generation sequencing technology.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pathway enrichment analysis revealed KRAS mutations were predominant in
      distal GT, while BRAF V600E mutations were more prevalent in proximal
      locations.
    explanation: >-
      Documents somatic KRAS mutation in glomus tumor and its enrichment in
      distal lesions, the mirror image of the BRAF V600E distribution.
- name: NF1
  gene_term:
    preferred_term: NF1
    term:
      id: hgnc:7765
      label: NF1
  variant_origin: GERMLINE
  relationship_type: SUSCEPTIBILITY
  notes: >-
    Germline NF1 loss-of-function variants predispose to digital glomus tumors,
    which are now recognized as part of the NF1 tumor spectrum. Lesions arise by
    biallelic inactivation, the somatic second hit frequently being copy-neutral
    loss of heterozygosity via mitotic recombination of 17q.
  evidence:
  - reference: PMID:19738042
    reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumors of the fingers or toes should be considered as part of the
      tumor spectrum of NF1.
    explanation: >-
      Establishes germline NF1 as a susceptibility genotype for digital glomus
      tumor.
- name: GLMN
  gene_term:
    preferred_term: GLMN
    term:
      id: hgnc:14373
      label: GLMN
  variant_origin: GERMLINE
  notes: >-
    Germline truncating variants in GLMN (glomulin) cause inherited glomuvenous
    malformation, with four founder mutations accounting for roughly two thirds
    of families. Penetrance is incomplete and lesions are focal, reflecting a
    paradominant mechanism that requires a somatic second hit, usually acquired
    uniparental isodisomy of chromosome 1p.
  evidence:
  - reference: PMID:15689436
    reference_title: 'Four common glomulin mutations cause two thirds of glomuvenous malformations ("familial glomangiomas"): evidence for a founder effect.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This finding suggests that GVM results from complete localised loss of
      function and explains the paradominant mode of inheritance.
    explanation: >-
      Establishes GLMN loss of function and the paradominant inheritance model
      for glomuvenous malformation.
differential_diagnoses:
- name: Jugulotympanic paraganglioma ("glomus jugulare" / "glomus tympanicum")
  description: >-
    This is a NAMING COLLISION, not a biological differential. The skull-base and
    middle-ear tumours historically called "glomus jugulare" and "glomus
    tympanicum" are PARAGANGLIOMAS and are NOT glomus tumours in the sense of
    this entry. They arise from neural-crest-derived parasympathetic paraganglia
    of the jugular bulb and tympanic plexus, are neuroendocrine (chromogranin /
    synaptophysin positive, with S100/SOX10-positive sustentacular cells), are
    associated with germline SDHx variants, may be catecholamine-secreting, and
    are managed by skull-base surgery or stereotactic radiosurgery. They share
    nothing with the pericytic MIR143-NOTCH-driven soft-tissue glomus tumour
    except the nineteenth-century use of "glomus" for a vascular body. Anyone
    reaching this entry from a "glomus jugulare" query has the wrong entity: see
    MONDO:0021064 (jugulotympanic paraganglioma) instead.
  disease_term:
    preferred_term: jugulotympanic paraganglioma
    term:
      id: MONDO:0021064
      label: jugulotympanic paraganglioma
  distinguishing_features:
  - Anatomic site is the jugular foramen / middle ear rather than the acral soft tissue or nail bed
  - Neuroendocrine chief-cell morphology with chromogranin and synaptophysin expression, and S100/SOX10-positive sustentacular cells; glomus tumour is S100-negative and actin-positive
  - Derived from neural-crest paraganglia, not from perivascular modified smooth muscle
  - Germline SDHx predisposition; no MIR143-NOTCH fusion
  - May secrete catecholamines and present with pulsatile tinnitus and lower cranial neuropathy, not with the paroxysmal-pain/cold-sensitivity triad
  evidence:
  - reference: PMID:42349676
    reference_title: 'Jugular Foramen Paraganglioma (Glomus Jugulare): A 10-Year Single-Center Experience.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Jugulotympanic paragangliomas (JTPs) are rare, hypervascular skull base
      tumors.
    explanation: >-
      Confirms that the entity clinically called "glomus jugulare" is a
      jugulotympanic paraganglioma of the skull base - a different disease from
      the acral pericytic glomus tumour modelled here.
  - reference: PMID:20530151
    reference_title: 'Diagnosis, management, and complications of glomus tumours of the digits in neurofibromatosis type 1.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus bodies are thermoregulatory shunts concentrated in the dermis of
      the fingertips and other peripheral sites subject to excessive cold and
      should be distinguished from unrelated adrenal and extra-adrenal
      paragangliomas, also commonly called "glomus tumors."
    explanation: >-
      The glomus-tumour literature itself instructs readers to keep the
      thermoregulatory glomus body distinct from the unrelated paragangliomas
      that share the "glomus tumour" name - an authoritative statement of the
      naming collision this differential exists to prevent.
  notes: >-
    Curation guardrail. This is the single most consequential entity-resolution
    error for this disease name, and it is exactly the Named Entity Confusion
    failure mode described in CLAUDE.md: literature retrieved for "glomus tumor"
    will silently include head-and-neck paraganglioma papers whose PMIDs are real
    and whose snippets validate. Check that any candidate reference is about an
    acral/soft-tissue lesion before citing it here.
- name: Myopericytoma
  description: >-
    A member of the same pericytic/perivascular myoid tumour family, showing
    concentric perivascular growth of myoid cells. Morphologic overlap with
    glomus tumour is substantial, and the two are separated most cleanly at the
    molecular level: myopericytoma and myofibroma carry PDGFRB mutations whereas
    glomus tumour carries NOTCH fusions.
  disease_term:
    preferred_term: myopericytoma
    term:
      id: MONDO:0017349
      label: myopericytoma
  distinguishing_features:
  - Concentric multilayered perivascular myoid whorls rather than sheets of uniform round glomus cells with sharply defined borders
  - PDGFRB-mutant rather than NOTCH-fusion positive
  - Usually painless, in contrast to the paroxysmal-pain triad of subungual glomus tumour
  evidence:
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They share variable histologic overlap with other tumors in the pericytic
      family including myofibroma (MF), myopericytoma (MP) and angioleiomyoma
      (AL).
    explanation: >-
      Names myopericytoma as a histologic mimic within the pericytic family.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the emerging genetic data suggest a dichotomy of the perivascular myoid
      tumor spectrum into 2 categories: PDGFRB-mutant MF and MP and NOTCH-fusion
      positive GT.
    explanation: >-
      Supplies the molecular discriminator that separates myopericytoma /
      myofibroma from glomus tumour.
- name: Angioleiomyoma
  description: >-
    A benign dermal or subcutaneous neoplasm of well-differentiated smooth
    muscle arranged around numerous vessels. Like glomus tumour it is a painful
    vascular-rich subcutaneous nodule of the extremities, so it is a genuine
    clinical as well as histologic mimic; unlike glomus tumour its cells are
    frankly spindled and strongly desmin-positive.
  disease_term:
    preferred_term: angioleiomyoma
    term:
      id: MONDO:0006646
      label: angioleiomyoma
  distinguishing_features:
  - Intersecting fascicles of elongated, cigar-shaped smooth muscle cells rather than rounded glomus cells with punched-out nuclei
  - Diffusely and strongly desmin-positive; glomus tumour is desmin-negative or only focally positive
  - Not NOTCH-fusion driven
  - Typically a deeper subcutaneous lower-limb nodule rather than a subungual lesion
  evidence:
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They share variable histologic overlap with other tumors in the pericytic
      family including myofibroma (MF), myopericytoma (MP) and angioleiomyoma
      (AL).
    explanation: >-
      Names angioleiomyoma as a histologic mimic within the pericytic family.
  - reference: PMID:1848411
    reference_title: 'Cutaneous glomus tumor. A comparative immunohistochemical study with pseudoangiomatous intradermal melanocytic nevi.'
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      all tumors were immunoreactive for muscle-specific actin, but only two
      expressed desmin
    explanation: >-
      Supplies the glomus-tumour side of the desmin discriminator (variable to
      negative); the angioleiomyoma comparison is standard diagnostic practice
      not measured in this paper, hence PARTIAL.
- name: GLI1-altered soft tissue tumour (GLI1-fused or GLI1-amplified)
  description: >-
    The most contemporary addition to the pericytic/perivascular differential. A
    distinct group of soft tissue neoplasms defined either by GLI1 gene fusions
    (ACTB, MALAT1 or PTCH1 partners) or by GLI1 amplification with CDK4 and MDM2
    co-amplification shows monomorphic ovoid-to-epithelioid cells in a
    nested-trabecular pattern separated by thin septa and a delicate capillary
    network. The authors of the defining series call this architecture highly
    reminiscent of glomus tumour and list glomus tumour/myopericytoma explicitly
    among the differential diagnoses. The distinction is prognostic, not
    academic: unlike conventional glomus tumour these are malignant soft tissue
    tumours, with high mitotic counts, necrosis, lymphovascular invasion and
    documented lymph node and lung metastases, and they cannot be separated from
    glomus tumour on morphology alone.
  distinguishing_features:
  - GLI1 gene fusion, or GLI1 amplification usually with CDK4 and MDM2 co-amplification, rather than a MIR143-NOTCH fusion
  - Frequent S100 positivity and an inconsistent immunoprofile (CD56, SMA, pan-CK variably positive); glomus tumour is consistently actin-positive and S100-negative
  - High mitotic count and necrosis in a substantial minority, with lymphovascular invasion
  - Malignant behaviour is the rule rather than the rare exception it is in glomus tumour
  evidence:
  - reference: PMID:31189998
    reference_title: GLI1-amplifications expand the spectrum of soft tissue neoplasms defined by GLI1 gene fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumors are consistently positive for actin and show the
      miR143-NOTCH2 gene fusion in most cases
    explanation: >-
      The defining GLI1 series states the discriminator from the glomus-tumour
      side - consistent actin positivity plus the MIR143-NOTCH2 fusion - when
      setting out its own differential diagnosis.
  - reference: PMID:31189998
    reference_title: GLI1-amplifications expand the spectrum of soft tissue neoplasms defined by GLI1 gene fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      FISH showed GLI1 (12q13.3) gene amplification in all 10 cases, with
      co-amplification of CDK4 (12q14.1) in nine (90%) and MDM2 (12q15) in eight
      (80%) cases.
    explanation: >-
      Supplies the molecular signature that separates this group from glomus
      tumour.
  - reference: PMID:31189998
    reference_title: GLI1-amplifications expand the spectrum of soft tissue neoplasms defined by GLI1 gene fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      No consistent immunoprofile was detected, with positivity for CD56 (six
      cases), S100 (four cases), SMA (two cases), and pan-CK (one case).
    explanation: >-
      Documents the inconsistent, frequently S100-positive immunoprofile, the
      inverse of the uniform actin-positive, S100-negative glomus tumour
      phenotype.
  notes: >-
    MONDO has no class for GLI1-altered / GLI1-amplified soft tissue tumour (a
    MONDO search for "GLI1" returns only the HGNC gene record), so this
    differential is deliberately recorded without a disease_term rather than
    mapped to an approximate parent.
- name: Solitary fibrous tumour (formerly haemangiopericytoma)
  description: >-
    Historically confused with glomus tumour because "haemangiopericytoma" was
    once used for any perivascular-patterned tumour. Solitary fibrous tumour is
    now defined by the NAB2-STAT6 fusion with nuclear STAT6 expression and CD34
    positivity, and is a fibroblastic rather than pericytic lesion; the
    staghorn-vessel pattern it shares with glomus tumour is a non-specific
    architectural feature.
  disease_term:
    preferred_term: solitary fibrous tumor
    term:
      id: MONDO:0016238
      label: solitary fibrous tumor
  distinguishing_features:
  - Patternless spindle-cell proliferation with ropey collagen and staghorn vessels, not uniform round perivascular glomus cells
  - Nuclear STAT6 (NAB2-STAT6 fusion) and CD34 positive; glomus tumour is STAT6/CD34 negative and SMA positive
  - Fibroblastic lineage, not pericytic; no NOTCH fusion
  - Typically a deep-seated or serosal mass, painless, without the cold-sensitivity triad
  evidence:
  - reference: PMID:24030747
    reference_title: Nuclear expression of STAT6 distinguishes solitary fibrous tumor from histologic mimics.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In conclusion, STAT6 is a highly sensitive and almost perfectly specific
      immunohistochemical marker for SFT and can be helpful to distinguish this
      tumor type from histologic mimics.
    explanation: >-
      Validates nuclear STAT6 as the discriminator that separates solitary
      fibrous tumour from its histologic mimics, glomus tumour among them.
  - reference: PMID:24030747
    reference_title: Nuclear expression of STAT6 distinguishes solitary fibrous tumor from histologic mimics.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fifty-nine of 60 SFT cases (98%) showed nuclear expression of STAT6, which
      was usually diffuse and intense. All other tumor types were negative for
      STAT6, except for three dedifferentiated liposarcomas and one deep fibrous
      histiocytoma, which showed weak staining.
    explanation: >-
      Quantifies the operating characteristics of the STAT6 discriminator across
      231 soft tissue tumours, establishing that a STAT6-negative perivascular
      lesion is not a solitary fibrous tumour.
  - reference: PMID:31189998
    reference_title: GLI1-amplifications expand the spectrum of soft tissue neoplasms defined by GLI1 gene fusions.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumors are consistently positive for actin and show the
      miR143-NOTCH2 gene fusion in most cases
    explanation: >-
      Supplies the glomus-tumour side of the discriminator (actin positivity
      plus MIR143-NOTCH2 fusion) in a paper that discusses solitary fibrous
      tumour and glomus tumour together on the same differential; it does not
      itself compare the two head to head, hence PARTIAL.
  notes: >-
    Historically this differential carried no evidence item because no abstract
    in the reference set made the glomus-tumour-versus-SFT comparison directly.
    It is now backed from both sides: the NAB2-STAT6 / nuclear STAT6
    discriminator by PMID:24030747, and the actin-plus-MIR143-NOTCH2
    glomus-tumour signature by PMID:31189998, which lists solitary fibrous
    tumour and glomus tumour/myopericytoma on the same differential. A single
    paper making the head-to-head comparison still does not appear to exist.
- name: Eccrine spiradenoma
  description: >-
    A benign sweat-gland adnexal neoplasm and one of the classic causes of a
    small, exquisitely painful dermal nodule. It sits alongside glomus tumour on
    the standard differential for a painful cutaneous or subungual nodule, but is
    an epithelial (basaloid) tumour rather than a perivascular myoid one.
  disease_term:
    preferred_term: benign spiradenoma
    term:
      id: MONDO:0003448
      label: benign spiradenoma
  distinguishing_features:
  - Basaloid epithelial nodules with two cell populations and scattered lymphocytes, not perivascular myoid cells
  - Cytokeratin-positive and SMA-negative in the neoplastic cells, the inverse of the glomus tumour immunophenotype
  - No cold hypersensitivity or Hildreth response
  - More often trunk or proximal-extremity dermis than subungual
  evidence:
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      differential diagnosis of other painful tumours, such as leiomyoma,
      eccrine spiradenoma, haemangioma, neuroma, osteochondroma, or mucous cyst
      should always be kept in mind while evaluating a patient with severe pain
      in the tip of the finger.
    explanation: >-
      Places eccrine spiradenoma explicitly on the differential for a painful
      fingertip lesion, together with the other painful-tumour mimics.
- name: Other painful acral lesions (leiomyoma, haemangioma, neuroma, osteochondroma, mucous cyst)
  description: >-
    A cluster of lesions that share the presenting complaint - severe pain at the
    fingertip - but not the mechanism. They are grouped here because the review
    literature enumerates them together as the standing differential for a
    painful digital lesion, and because diagnostic delay in glomus tumour is
    typically caused by one of them being assumed instead.
  distinguishing_features:
  - None reproduces the full triad of paroxysmal pain, pinpoint tenderness and cold hypersensitivity with a positive Hildreth response
  - Contrast-enhanced high-resolution MRI distinguishes most of them from the avidly enhancing, T2-hyperintense glomus tumour
  - Definitive separation is histopathologic
  evidence:
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      differential diagnosis of other painful tumours, such as leiomyoma,
      eccrine spiradenoma, haemangioma, neuroma, osteochondroma, or mucous cyst
      should always be kept in mind while evaluating a patient with severe pain
      in the tip of the finger.
    explanation: >-
      Enumerates the standing differential for a painful fingertip lesion.
- name: Glomuvenous malformation (GLMN-related)
  description: >-
    Modelled in this entry as a subtype rather than a wholly separate disease,
    but the boundary matters and is easy to blur. Sporadic solitary glomus tumour
    is a somatic, fusion-driven NEOPLASM; glomuvenous malformation is an
    inherited GLMN-related vascular MALFORMATION in which a somatic second hit
    (usually acquired uniparental isodisomy of 1p) unmasks the germline allele
    locally. They are not two presentations of one lesion, and evidence about one
    must not be transferred to the other.
  disease_term:
    preferred_term: glomuvenous malformation
    term:
      id: MONDO:0007672
      label: glomuvenous malformation
  distinguishing_features:
  - Multiple, multifocal, compressible blue-purple plaques rather than a solitary subungual nodule
  - Much less painful, and pain is not paroxysmal or cold-provoked
  - Germline GLMN loss of function with a somatic second hit (paradominant), not a MIR143-NOTCH fusion
  - Dilated venous channels with only a few layers of glomus cells, rather than solid sheets of glomus cells
  evidence:
  - reference: PMID:15689436
    reference_title: 'Four common glomulin mutations cause two thirds of glomuvenous malformations ("familial glomangiomas"): evidence for a founder effect.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomuvenous malformation (GVM) ("familial glomangioma") is a localised
      cutaneous vascular lesion histologically characterised by abnormal smooth
      muscle-like "glomus cells" in the walls of distended endothelium lined
      channels.
    explanation: >-
      Defines GVM as a vascular lesion with glomus cells in the channel walls,
      distinct in architecture from the solid sporadic glomus tumour.
  - reference: PMID:23375657
    reference_title: Somatic uniparental isodisomy explains multifocality of glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This finding demonstrates that a double hit is needed to trigger formation
      of a GVM.
    explanation: >-
      Establishes the germline-plus-somatic two-hit genetics that distinguishes
      GVM from the purely somatic sporadic glomus tumour.
inheritance:
- name: Autosomal dominant inheritance of glomuvenous malformation
  description: >-
    Familial multiple glomangioma (glomuvenous malformation) segregates as an
    autosomal dominant trait caused by GLMN loss-of-function variants, with
    incomplete penetrance and variable expressivity attributed to the requirement
    for a somatic second hit (paradominant inheritance).
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  evidence:
  - reference: PMID:23375657
    reference_title: Somatic uniparental isodisomy explains multifocality of glomuvenous malformations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Inherited vascular malformations are commonly autosomal dominantly
      inherited with high, but incomplete, penetrance; they often present as
      multiple lesions.
    explanation: >-
      Describes the autosomal dominant, incompletely penetrant, multifocal
      inheritance pattern of glomuvenous malformation.
clinical_trials:
- name: NCT03422679
  phase: PHASE_I
  status: TERMINATED
  description: >-
    Dose-escalation study of CB-103, an oral pan-NOTCH transcription-complex
    inhibitor, in adults with locally advanced or metastatic solid tumours and
    haematological malignancies characterised by NOTCH pathway alterations.
    Malignant glomus tumor is one of the registry-indexed conditions, making this
    the first trial to prospectively select glomus tumors on the basis of their
    MIR143-NOTCH driver. Seventy-nine patients enrolled overall and the study was
    stopped early; the ClinicalTrials.gov record gives the reason for stopping as
    a business reason, not demonstrated inefficacy. The peer-reviewed phase I
    report found a manageable safety profile and pharmacodynamic evidence of
    Notch target-gene downregulation, but limited single-agent antitumor
    activity: no objective responses and stable disease in 49%. The population
    was dominated by adenoid cystic carcinoma (40 of 79, 51%) and no
    glomus-tumor-specific outcome was reported, so these basket-level results
    must not be attributed to the glomus subgroup in either direction.
  target_phenotypes:
  - preferred_term: Neoplasm
    term:
      id: HP:0002664
      label: Neoplasm
  evidence:
  - reference: clinicaltrials:NCT03422679
    reference_title: A Phase I/IIA, Multi-Centre, Open-Label, Dose-Escalation Study With Expansion Arms to Assess the Safety, Tolerability, Pharmacokinetics and Preliminary Efficacy of CB-103 Administered Orally in Adult Patients With Locally Advanced or Metastatic Solid Tumours and Haematological Malignancies Characterised by Alterations of the NOTCH Signalling Pathway
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      investigate the safety, tolerability and preliminary efficacy of CB-103
    explanation: >-
      Registry record for the NOTCH-pathway-selected basket trial that lists
      malignant glomus tumor among its conditions; the study was terminated, so
      it supports the therapeutic rationale rather than any efficacy claim.
  - reference: PMID:37712875
    reference_title: A Phase I Study of the Pan-Notch Inhibitor CB-103 for Patients with Advanced Adenoid Cystic Carcinoma and Other Tumors.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      CB-103 had a manageable safety profile and biological activity but limited
      clinical antitumor activity as monotherapy in this first-in-human study.
    explanation: >-
      The peer-reviewed phase I publication behind this registry record. It
      establishes tolerability and on-target biological activity but not
      efficacy, which is why the pan-NOTCH strategy remains a rationale rather
      than a treatment for malignant glomus tumor.
  - reference: PMID:37712875
    reference_title: A Phase I Study of the Pan-Notch Inhibitor CB-103 for Patients with Advanced Adenoid Cystic Carcinoma and Other Tumors.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There were no objective responses, but 37 (49%) had stable disease;
      including 23 of 40 (58%) patients with ACC.
    explanation: >-
      Gives the basket-level outcome. Adenoid cystic carcinoma dominated the
      cohort (40 of 79) and no glomus-tumor-specific response is reported, so
      this figure bounds what may be claimed for glomus tumor rather than
      supporting or refuting activity in it.
  notes: >-
    Two provenance points that matter for reading the TERMINATED status
    correctly. First, the ClinicalTrials.gov record states the reason for
    stopping as a business reason; that field is not present in the cached
    registry summary, so it is recorded here as prose rather than as an evidence
    snippet. Second, "terminated" here is not a negative efficacy verdict on
    glomus tumor: the phase I publication PMID:37712875 reports the outcome for
    an adenoid-cystic-carcinoma-dominated basket, with no glomus-tumor-specific
    result of any kind.
treatments:
- name: Complete Surgical Excision
  action_category: THERAPEUTIC
  therapeutic_modality: SURGERY
  description: >-
    Complete surgical excision, typically via a transungual or lateral
    subperiosteal approach for subungual lesions, is the definitive treatment for
    localized glomus tumor. It produces prompt and durable relief of pain;
    incomplete excision is the principal cause of symptomatic recurrence.
  treatment_term:
    preferred_term: Excision
    term:
      id: NCIT:C15232
      label: Excision
  target_mechanisms:
  - target: Glomus Cell Proliferation Around Distorted Vascular Channels
    treatment_effect: INHIBITS
    description: >-
      Excision physically removes the proliferating glomus cell mass and with it
      the nociceptor-rich stroma responsible for the pain syndrome.
    evidence:
    - reference: PMID:34239958
      reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        experienced complete symptomatic relief within 2-4 weeks after surgical
        excision
      explanation: >-
        Removal of the proliferating mass abolishes the pain syndrome in every
        patient, demonstrating that the excised node is the mechanistic source of
        the symptoms.
  evidence:
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      experienced complete symptomatic relief within 2-4 weeks after surgical
      excision
    explanation: >-
      Reports complete symptomatic relief in all 17 patients after excision, with
      no recurrence at one year.
  - reference: PMID:27857505
    reference_title: 'Glomus tumours of the hand: Review of literature.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Complete surgical excision is a must to get complete relief from the
      symptoms and to avoid recurrence.
    explanation: >-
      States that completeness of excision determines both symptom relief and
      freedom from recurrence.
  - reference: PMID:41693210
    reference_title: The Molecular Mechanism and Therapeutic Progress in Glomus Tumor.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      While complete surgical excision remains the standard curative treatment
      for localized disease
    explanation: >-
      Confirms complete excision as the standard curative therapy for localized
      glomus tumor.
- name: MEK Inhibition for NF1-Deficient Tumors
  action_category: THERAPEUTIC
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    For NF1-deficient glomus tumors there is no BRAF kinase to inhibit, so the
    proposed systemic strategy is direct MEK blockade downstream of the
    unrestrained RAS. This is an investigational, mechanism-derived rationale
    rather than an established standard: it is put forward in narrative review
    for multifocal, metastatic, or surgically challenging cases, and no
    glomus-tumor-specific trial or response series supports it yet. Selumetinib
    is named as the exemplar MEK inhibitor because it is the agent approved in
    NF1-associated plexiform neurofibroma, not because it has been tested in
    glomus tumor.
  treatment_term:
    preferred_term: Targeted Therapy
    term:
      id: NCIT:C93352
      label: Targeted Therapy
    therapeutic_agent:
    - preferred_term: selumetinib
      term:
        id: CHEBI:90227
        label: selumetinib
  target_mechanisms:
  - target: Constitutive Mitogenic Pathway Activation
    treatment_effect: INHIBITS
    description: >-
      MEK inhibition blocks the RAS-MAPK cascade immediately downstream of the
      RAS node that neurofibromin loss leaves unrestrained.
    evidence:
    - reference: PMID:41693210
      reference_title: The Molecular Mechanism and Therapeutic Progress in Glomus Tumor.
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        molecular insights have spurred investigation into targeted agents,
        including MEK inhibitors for NF1-deficient tumors and immunotherapy
      explanation: >-
        States the MEK-inhibition rationale for NF1-deficient glomus tumors; it
        is framed as investigation spurred by molecular insight, not as
        demonstrated efficacy, hence PARTIAL.
  evidence:
  - reference: PMID:41693210
    reference_title: The Molecular Mechanism and Therapeutic Progress in Glomus Tumor.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Such systemic therapies are particularly relevant for multifocal,
      metastatic, or surgically challenging cases.
    explanation: >-
      Scopes the systemic-therapy indication to unresectable/multifocal disease;
      no efficacy data are reported, so this remains investigational.
  - reference: PMID:19738042
    reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      RAS mitogen-activated protein kinase hyperactivation was observed in
      cultured NF1(-/-) glomus cells, reflecting a lack of inhibition of the
      pathway by functional neurofibromin, the protein product of NF1.
    explanation: >-
      Supplies the mechanistic target: cultured NF1-null glomus cells show the
      RAS-MAPK hyperactivation that a MEK inhibitor would suppress.
- name: BRAF and MEK Inhibition
  action_category: THERAPEUTIC
  therapeutic_modality: SMALL_MOLECULE
  description: >-
    For metastatic malignant glomus tumor harboring BRAF p.Val600Glu, combined
    BRAF and MEK inhibition with encorafenib plus binimetinib has produced a
    complete clinical and morpho-metabolic response. Evidence is limited to case
    reports, and conventional chemotherapy is poorly effective in this setting.
  treatment_term:
    preferred_term: Targeted Therapy
    term:
      id: NCIT:C93352
      label: Targeted Therapy
    therapeutic_agent:
    - preferred_term: encorafenib
      term:
        id: NCIT:C98283
        label: Encorafenib
    - preferred_term: binimetinib
      term:
        id: CHEBI:145371
        label: binimetinib
  target_mechanisms:
  - target: Constitutive Mitogenic Pathway Activation
    treatment_effect: INHIBITS
    description: >-
      Encorafenib inhibits the mutant BRAF kinase and binimetinib blocks
      downstream MEK, shutting off the constitutive RAS-MAPK output that drives
      proliferation.
    evidence:
    - reference: PMID:39392364
      reference_title: Complete response to encorafenib plus binimetinib in a BRAF V600E-mutant metastasic malignant glomus tumor.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The BRAF V600E mutation has been identified in a subset of malignant GT,
        highlighting a promising therapeutic target.
      explanation: >-
        Identifies BRAF V600E as the actionable target of the combination in
        malignant glomus tumor.
  evidence:
  - reference: PMID:39392364
    reference_title: Complete response to encorafenib plus binimetinib in a BRAF V600E-mutant metastasic malignant glomus tumor.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here, we report the impressive clinical and morpho-metabolic response of a
      metastatic BRAF V600E-mutated glomangiosarcoma after treatment with
      encorafenib and binimetinib.
    explanation: >-
      Single-case evidence of response; supportive but not sufficient to
      establish standard-of-care status.
- name: Symptom-Directed Surveillance for Digital Glomus Tumour in NF1
  action_category: SCREENING
  description: >-
    Digital glomus tumour is part of the NF1 tumour spectrum and is the most
    under-recognised member of it, so the 2023 ERN GENTURIS NF1 tumour
    surveillance guideline manages it by symptom-directed clinical vigilance
    rather than by imaging. Adults with NF1 are assessed clinically at least
    once every three years, and every visit includes history taking and, for
    this tumour, direct questioning about localised tenderness, severe
    paroxysmal pain and cold sensitivity in the fingers and toes together with
    visual inspection of the nail beds and palpation. No routine imaging of
    asymptomatic digits is recommended. The rationale is diagnostic delay rather
    than mortality: patients frequently live with the pain for years without the
    diagnosis being considered, so the yield comes from asking. Because
    NF1-associated lesions are more often multifocal and both local recurrence
    and metachronous tumours are common, excision of one lesion does not end
    surveillance.
  treatment_term:
    preferred_term: periodic clinical assessment with nail-bed inspection and symptom enquiry
    term:
      id: NCIT:C20989
      label: Physical Examination
  evidence:
  - reference: PMID:36684394
    reference_title: ERN GENTURIS tumour surveillance guidelines for individuals with neurofibromatosis type 1.
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Given the oncogenic potential, long-term surveillance is important in
      patients with NF1.
    explanation: >-
      The European Reference Network guideline that frames tumour surveillance
      as standard care in NF1. PARTIAL because the glomus-specific
      recommendations sit in the guideline's full text rather than its abstract
      (see notes).
  - reference: PMID:20530151
    reference_title: 'Diagnosis, management, and complications of glomus tumours of the digits in neurofibromatosis type 1.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Glomus tumours in NF1 are more common than previously recognised and NF1
      patients should be specifically queried about fingertip or toe pain.
    explanation: >-
      States the surveillance action itself - direct symptom enquiry in every
      NF1 patient - and is the primary series the GENTURIS guideline cites for
      its glomus tumour recommendations.
  - reference: PMID:20530151
    reference_title: 'Diagnosis, management, and complications of glomus tumours of the digits in neurofibromatosis type 1.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is often a delay in diagnosis of many years and clinical suspicion
      is key to diagnosis, although magnetic resonance imaging may be useful in
      some scenarios.
    explanation: >-
      Supplies the rationale for symptom-directed vigilance rather than routine
      imaging, and the reason surveillance is worthwhile at all.
  - reference: PMID:20530151
    reference_title: 'Diagnosis, management, and complications of glomus tumours of the digits in neurofibromatosis type 1.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Surgical extirpation can be curative; however, local tumour recurrence and
      metachronous tumours are common.
    explanation: >-
      Establishes that surveillance must continue after excision in NF1, because
      recurrence and new metachronous lesions are expected.
  notes: >-
    Provenance caveat. The glomus-specific content of the GENTURIS guideline -
    its Table 13 recommendations and the at-least-three-yearly adult clinical
    assessment - is in the full text of PMID:36684394, whereas the local
    reference cache for that PMID contains the abstract only. Rather than quote
    text that cannot be verified against the cache, the GENTURIS evidence item
    is quoted at abstract level and marked PARTIAL, and the glomus-specific
    actions are evidenced from PMID:20530151, the primary multi-institutional
    series the guideline cites for them.
discussions:
- discussion_id: glomus-subungual-fusion-negative
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    What drives the classic painful subungual glomus tumor, given that this
    commonest subset lacks the MIR143-NOTCH fusions that define the disease
    molecularly?
  attaches_to:
  - pathophysiology#MIR143-NOTCH Gene Fusion
  rationale: >-
    The molecular model of glomus tumor rests on MIR143-NOTCH fusions found in
    over half of tumors, but the same cohort reports that the common subungual
    subset - the lesions that produce the classic clinical triad and account for
    most clinical practice - is fusion-negative. The BRAF/KRAS and NF1 arms do
    not fill the gap either: sporadic tumors showed no NF1 or RAS-MAPK
    abnormality, and BRAF V600E is enriched in proximal rather than distal
    lesions. The entry therefore models a driver landscape that does not explain
    its own flagship phenotype. Until this is resolved, no causal edge should be
    drawn from the fusion node to the subungual presentation.
  proposed_experiments:
  - experiment_id: exp_glomus_subungual_fusion_negative_rnaseq
    name: RNA sequencing of fusion-negative subungual glomus tumors
    description: >-
      Sequence a dedicated cohort of classic painful subungual glomus tumors
      confirmed NOTCH-fusion-negative by break-apart FISH, to search for
      alternative fusions, cryptic NOTCH-pathway lesions, or an entirely distinct
      driver class.
  - experiment_id: exp_glomus_site_stratified_profiling
    name: Site-stratified methylation and single-cell profiling
    description: >-
      Compare subungual with deep and visceral glomus tumors by DNA methylation
      classification and single-cell profiling, to test whether they are one
      entity reached by two driver routes or two entities that converge on a
      shared morphology.
  evidence:
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The common subungual GT subset lack NOTCH-gene fusions suggesting an
      alternative pathogenesis.
    explanation: >-
      States the gap directly: the commonest clinical subset is not explained by
      the defining molecular driver.
  - reference: PMID:19738042
    reference_title: 'Glomus tumors in neurofibromatosis type 1: genetic, functional, and clinical evidence of a novel association.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      No abnormalities in NF1 or RAS mitogen-activated protein kinase activation
      were found in sporadic glomus tumors.
    explanation: >-
      Excludes the NF1/RAS-MAPK route as the alternative driver in sporadic
      tumors, narrowing the gap.
- discussion_id: glomus-epidemiology-gap
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    What is the population incidence of glomus tumor, and is the reported sex
    predominance real or an artifact of which anatomic subset a series samples?
  rationale: >-
    No population-based rate exists, so the prevalence record on this entry
    carries only the qualitative RARE band. The sex data are also internally
    inconsistent across the cited series in a way that looks anatomic rather
    than biological: a hand-only series reports 71% female, whereas a
    molecular-pathology cohort dominated by deep, visceral and NOTCH-rearranged
    tumors reports 82% male among benign fusion-positive cases. These may be two
    different populations rather than a contradiction, but the entry does not
    assert a sex ratio because the evidence cannot currently distinguish those
    possibilities.
  proposed_experiments:
  - experiment_id: exp_glomus_registry_incidence
    name: Registry-based incidence estimation
    description: >-
      Estimate glomus tumor incidence from a population cancer or national
      pathology registry (e.g. SEER), stratified by acral versus deep/visceral
      site, to replace the current qualitative RARE band with a rate.
  - experiment_id: exp_glomus_pooled_sex_ratio
    name: Site-stratified pooled analysis of sex ratio
    description: >-
      Pool published glomus tumor series with site stratification to test whether
      the apparent contradiction between female-predominant hand series and
      male-predominant deep/visceral molecular cohorts is explained by anatomic
      sampling.
  evidence:
  - reference: PMID:34239958
    reference_title: Presentation and Management Outcome of Glomus Tumors of the Hand.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Out of 17 patients, majority (n=12; 70.58%) were females.
    explanation: >-
      The female-predominant hand series.
  - reference: PMID:32604167
    reference_title: A Molecular Reappraisal of Glomus Tumors and Related Pericytic Neoplasms With Emphasis on NOTCH-gene Fusions.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among the 34 cases of benign NOTCH-rearranged GT, most occurred in males
      (n=28, 82%)
    explanation: >-
      The male-predominant molecular cohort, drawn from a different anatomic
      distribution.
- discussion_id: glomus-icdo-morphology-unrepresentable
  kind: CURATION_TODO
  status: OPEN
  prompt: >-
    Where should the ICD-O morphology codes 8711/0 (glomus tumour, benign) and
    8711/3 (glomangiosarcoma) be recorded?
  rationale: >-
    MONDO:0018327 carries the xref ICDO:8711/0, but neither the coarse
    ICDOMorphologyEnum used by classifications.icdo_morphology (whose ten values
    are Carcinoma, Adenocarcinoma, Squamous Cell Carcinoma, Sarcoma, Leukemia,
    Lymphoma, Multiple Myeloma, Melanoma, Glioma, Embryonal Neoplasm) nor
    DiseaseMappings (icd10cm/icd11f/mondo/ncit only) can hold a four-digit ICD-O
    morphology code. Assigning "Sarcoma" would be wrong, since the great majority
    of glomus tumours are benign. The classifications block is therefore
    deliberately omitted from this entry rather than populated incorrectly.
    Resolving this needs a schema change, not a curation change.
  notes: >-
    Escalated to a schema issue as monarch-initiative/dismech#7548 (assigned to
    @cmungall) during review of PR #7484. When that issue is resolved, populate
    this entry with ICD-O 8711/0 for the benign entity and 8711/3 for the
    malignant glomus tumour subtype, then close this discussion.

📚

References & Deep Research

Deep Research

1

Falcon ▸

Glomus Tumor: Disease Characteristics Research Report

Edison Scientific Literature 17 citations 2026-07-31T17:11:43.099029

Glomus Tumor: Disease Characteristics Research Report

Scope. This report concerns the soft-tissue glomus tumor, a perivascular/pericytic neoplasm showing differentiation toward modified smooth-muscle cells of the normal glomus body. It does not concern “glomus jugulare,” “glomus tympanicum,” or carotid-body tumors, which are paragangliomas with different cells of origin, genetics, management, and ontology mappings.

Evidence note. Glomus tumor is rare, and much of the literature consists of retrospective series and case reports. The strongest retrieved recent evidence comprised a 2023 NF1 surveillance guideline and the 2024 ClinicalTrials.gov update of a molecularly selected malignant-glomus-tumor trial. Some requested database fields could not be validated from accessible primary sources and are therefore marked as unconfirmed rather than inferred.

Domain	Established finding	Evidence/recency	Suggested ontology terms
Scope/definition	Soft-tissue glomus tumor is the target entity here; it is a pericytic/glomus-cell neoplasm and should not be conflated with glomus jugulare/tympanicum paraganglioma. ClinicalTrials.gov indexes “Glomus Tumor” under MeSH D005918; NOTCH-focused malignant glomus tumor trial eligibility further supports this soft-tissue usage. (NCT03422679 chunk 1, NCT03422679 chunk 2)	Clinical registry evidence, updated 2024-01-16; mechanistic review notes glomus tumors as a subset of pericytic tumours with MIR143-NOTCH fusions. (gaudio2022notchsignallingin pages 10-11, NCT03422679 chunk 1, NCT03422679 chunk 2)	MeSH: D005918 Glomus Tumor; NCIT: Glomus Tumor; MONDO: not confirmed from available context
Typical phenotype	Classic presentation is a small painful lesion, often digital/subungual, with marked tenderness and often cold sensitivity; extradigital and visceral tumors also occur. NF1 guidance specifically mentions glomus tumours of the digits in adults. (carton2023erngenturistumour pages 7-8)	Mixed evidence base; strong clinical tradition, but only digit localization is directly supported in retrieved context. NF1 surveillance guideline is 2023. (carton2023erngenturistumour pages 7-8)	HPO: Pain (HP:0012531), Tenderness (HP:0033748), Abnormality of the nail (HP:0001597), Cold-induced pain suggested term if curated
Anatomy	Common sites include digits/finger, but glomus tumors can also occur in soft tissue of limbs, trunk, head/neck, and less commonly stomach, bone, tongue, lung in fusion-defined or related pericytic neoplasms. (agaram2019gli1amplificationsexpandthe pages 1-2)	Molecular pathology review/series context; 2019-2022 evidence indicates broad anatomic spectrum for pericytic tumors with related signaling lesions. (agaram2019gli1amplificationsexpandthe pages 1-2, gaudio2022notchsignallingin pages 10-11)	UBERON: finger (UBERON:0002389), nail unit (suggested), soft tissue of upper limb/lower limb (suggested), stomach (UBERON:0000945)
Histology/IHC	Histology typically shows uniform round/ovoid to epithelioid cells in nests/trabeculae around a delicate vascular network. In related pericytic tumors, smooth muscle actin (SMA) and laminin/collagen IV-type pericellular basement membrane support pericytic/glomus differentiation; immunophenotype may be variable. (agaram2019gli1amplificationsexpandthe pages 1-2, gaudio2022notchsignallingin pages 10-11)	Pathology/mechanistic review evidence; 2019-2022. GLI1-amplified comparator series emphasizes nested epithelioid morphology and variable SMA positivity, useful in differential diagnosis. (agaram2019gli1amplificationsexpandthe pages 1-2, gaudio2022notchsignallingin pages 10-11)	GO/CL/NCIT suggestions: vascular smooth muscle cell differentiation (GO:0051146), pericyte (CL:0000669), smooth muscle actin positive pathology annotation
Somatic genetics: MIR143-NOTCH	MIR143-NOTCH1/2/3 fusions are a major recurrent driver in glomus tumors; review text states these fusions are found in almost 50% of glomus tumours. This supports aberrant NOTCH pathway activation as an upstream oncogenic mechanism. (gaudio2022notchsignallingin pages 10-11, mertens2016genefusionsin pages 19-20)	Mechanistic review 2022 citing primary fusion literature; gene-fusion review 2016 notes MIR143-NOTCH fusions in both benign and malignant lesions. (gaudio2022notchsignallingin pages 10-11, mertens2016genefusionsin pages 19-20)	HGNC: MIR143HG, NOTCH1, NOTCH2, NOTCH3; GO: Notch signaling pathway (GO:0007219)
Somatic genetics: BRAF	BRAF-mutant glomus tumors are a recognized subset, reported in the literature and associated with malignant histologic characteristics; however, precise frequency is not available from retrieved full-text context here.	Evidence present only indirectly in retrieved search metadata/unobtainable citation trail; supportive but not directly quotable from available contexts.	HGNC: BRAF; GO: MAPK cascade (GO:0000165)
Germline associations	NF1 is an established predisposition context for digital glomus tumors; the 2023 ERN GENTURIS NF1 guideline lists glomus tumours of the digits among tumors with increased adult risk. By contrast, GLMN (glomulin) classically underlies glomuvenous malformation/glomangioma, which is related but distinct from typical solitary soft-tissue glomus tumor. (carton2023erngenturistumour pages 7-8)	NF1 evidence is directly supported and 2023. GLMN distinction is standard disease-taxonomy knowledge but not directly documented in retrieved contexts, so should be curated cautiously. (carton2023erngenturistumour pages 7-8)	HGNC: NF1, GLMN; MONDO/Orphanet suggestions: Neurofibromatosis type 1, Glomuvenous malformation
Mechanism/pathophysiology	Working model: recurrent MIR143-driven NOTCH fusion places a strong smooth-muscle/pericytic regulatory locus upstream of NOTCH intracellular signaling, promoting abnormal perivascular cell growth and glomus-tumor phenotype. Reviews frame glomus tumors within dysregulated vascular NOTCH signaling. (gaudio2022notchsignallingin pages 10-11, mertens2016genefusionsin pages 19-20)	Mechanistic synthesis from review evidence 2016, 2022.	GO: Notch signaling pathway (GO:0007219), blood vessel morphogenesis (GO:0048514); CL: pericyte (CL:0000669)
Diagnosis	Diagnosis is usually based on clinical localization + imaging + excision pathology. For malignant/unusual cases, molecular testing for NOTCH pathway alterations can be clinically relevant, as shown by trial enrollment criteria requiring activating mutation or genetic lesion. (NCT03422679 chunk 1)	Direct clinical-trial evidence 2024 registry update; broader routine diagnostic specifics are not fully captured in available contexts. (NCT03422679 chunk 1)	NCIT: Magnetic Resonance Imaging, Biopsy, Surgical Excision, Molecular Diagnostic Testing
Treatment	For typical localized disease, standard care is complete surgical excision; no systemic standard is established for most benign tumors. For advanced malignant disease with NOTCH activation, investigational targeted therapy has included the pan-NOTCH inhibitor CB-103. (NCT03422679 chunk 1, NCT03422679 chunk 2)	Trial evidence current to 2024; localized surgical management is established practice but not directly detailed in retrieved full text.	NCIT: Surgical Excision, Targeted Therapy, CB-103 if mapped, Notch Pathway Inhibitor
Malignant disease/trial	Malignant glomus tumor is rare but clinically important. A dedicated phase I/II basket trial (NCT03422679) included “Glomus Tumor, Malignant” among eligible advanced solid tumors with NOTCH-pathway lesions; trial status was terminated for business reason, not efficacy. (NCT03422679 chunk 1, NCT03422679 chunk 2)	High-value recent implementation evidence: ClinicalTrials.gov results posted 2024-01-16. (NCT03422679 chunk 1, NCT03422679 chunk 2)	NCIT: Malignant Glomus Tumor, Advanced Solid Neoplasm, Clinical Trial
Prognosis	Benign solitary glomus tumors generally have excellent outcomes after complete excision; adverse behavior is mainly a concern in malignant/atypical lesions. Precise recurrence/metastasis rates are not available from retrieved contexts.	Inference from disease class and rarity literature; direct numeric prognosis data not captured in available full text.	HPO/NCIT suggestions: Recurrence, Metastatic malignant neoplasm
Prevention	No established primary prevention exists for sporadic glomus tumor. In NF1, practical prevention is limited to clinical vigilance/earlier recognition of symptomatic digital tumors rather than population screening. (carton2023erngenturistumour pages 7-8)	NF1 tumor-surveillance framework 2023 supports awareness-based secondary prevention.	NCIT: Surveillance, Genetic Counseling; HPO: symptom monitoring terms
Animal/models	No dedicated, well-established in vivo glomus tumor model was identified in the retrieved contexts. Mechanistic inference currently relies more on human tumor genomics and broader vascular NOTCH biology than on disease-specific models. (gaudio2022notchsignallingin pages 10-11)	Evidence gap, based on absence in retrieved literature and reliance on pathway reviews.	GO: Notch signaling pathway; model ontology terms: not available from current evidence
Evidence gaps	Key gaps from the available evidence set: validated MONDO/Orphanet mapping, robust epidemiology/incidence, direct HPO frequency estimates, standardized malignancy-risk biomarkers, disease-specific QoL data, curated GLMN vs glomus tumor boundary resources, and animal/model systems.	Important for curation quality; several requested knowledge-base fields remain under-supported by currently retrieved full text.	MONDO/HPO/UBERON/CL/NCIT mappings require targeted follow-up curation

Table: This compact table summarizes core disease-knowledge-base facts for soft-tissue glomus tumor while clearly separating it from paraganglioma terminology. It emphasizes molecular drivers, NF1 association, malignant-disease trial evidence, and current evidence gaps relevant for structured curation.

1. Disease information

Definition and classification

A glomus tumor is usually a small, circumscribed neoplasm of uniform round glomus cells arranged around branching vessels. It belongs to the pericytic/perivascular tumor family. Most lesions are benign and occur in the distal extremities, especially the subungual region; extradigital, deep-soft-tissue, visceral, and very rarely malignant tumors occur.

ClinicalTrials.gov and MeSH index the entity as Glomus Tumor, MeSH D005918. The registry places it under vascular-tissue and connective/soft-tissue neoplasms. The trial terminology “Glomus Tumor, Malignant” confirms that this indexing includes the malignant soft-tissue entity rather than only paraganglioma. (NCT03422679 chunk 1, NCT03422679 chunk 2)

Identifiers and suggested mappings

MeSH: D005918, Glomus Tumor—directly validated. (NCT03422679 chunk 2)
MONDO: a separate current MONDO identifier could not be validated from the retrieved sources; curate against the live MONDO release rather than assigning an uncertain ID.
OMIM/Orphanet: typical sporadic solitary glomus tumor does not have a single well-established Mendelian disease entry. Do not substitute entries for glomuvenous malformation caused by GLMN.
ICD-10-CM: coding is site and behavior dependent, commonly under benign neoplasm of connective/other soft tissue or uncertain/unknown behavior when appropriate; there is no universally satisfactory disease-specific code.
ICD-11: use morphology plus site/behavior coding after confirmation in the current release.
Category: pericytic/perivascular soft-tissue neoplasm; usually benign, rarely malignant.
Synonyms: glomus cell tumor, glomangioma, glomangiomyoma, solid glomus tumor. Strictly, the latter three may denote histologic variants and should not always be treated as exact synonyms. “Glomus jugulare tumor” is an excluded paraganglioma synonym.

This report synthesizes aggregated disease-level resources and published cohorts, not individual EHR-derived patient data. The ClinicalTrials.gov record is aggregated study-level information.

2. Etiology

Causal and genetic factors

Most solitary tumors are sporadic somatic neoplasms. The principal established molecular class has rearrangements joining the MIR143/MIR143HG locus to NOTCH1, NOTCH2, or NOTCH3. A vascular-NOTCH review reports that such fusions occur in “almost 50% of glomus tumours,” while a gene-fusion review notes their detection in both benign and malignant lesions. (gaudio2022notchsignallingin pages 10-11, mertens2016genefusionsin pages 19-20)

The strongest recognized constitutional association is neurofibromatosis type 1 (NF1), particularly with multiple or recurrent painful digital tumors. The 2023 ERN GENTURIS guideline states that in adulthood the risk of “glomus tumours of the digits” increases in NF1. This is an authoritative human guideline association, although it does not supply a penetrance estimate for glomus tumors. Published February 2023; DOI: 10.1016/j.eclinm.2022.101818. (carton2023erngenturistumour pages 7-8)

GLMN requires careful separation. Germline loss-of-function variants in GLMN cause autosomal-dominant glomuvenous malformations, historically called multiple glomangiomas. These vascular malformations overlap morphologically and terminologically with glomus tumors but are not equivalent to the typical solitary neoplasm. Variant-level ClinVar/gnomAD frequencies were not available in the retrieved evidence.

Somatic BRAF p.Val600Glu has been reported in a minority of glomus tumors and appears enriched among lesions with malignant histologic features, but an exact frequency was not recoverable from accessible full text and should not be entered without verification of the primary cohort.

Environmental, infectious, lifestyle, and protective factors

No reproducible causal association with smoking, alcohol, diet, toxins, radiation, occupation, infection, or trauma has been established. Trauma may bring a painful lesion to attention but is not a proven cause. No validated genetic or environmental protective factor is known. There is no demonstrated gene–environment interaction.

3. Phenotypes

The classic digital phenotype is a small, intensely painful nodule with pinpoint tenderness and cold hypersensitivity. Pain can be spontaneous or pressure-provoked and may substantially impair sleep, manual work, typing, footwear tolerance, and daily activities despite the tumor’s small size. Formal EQ-5D, SF-36, or PROMIS studies and reliable phenotype frequencies are lacking.

Suggested structured phenotypes include:

Localized pain: symptom; often severe and chronic/episodic; HP:0012531 Pain.
Tenderness: clinical sign, typically sharply localized; HP:0033748 Tenderness.
Cold-provoked pain/hypersensitivity: symptom; no confidently validated dedicated HPO identifier was established from retrieved evidence, so use a curated cold-sensitivity child term if available.
Subungual blue-red nodule or nail-bed discoloration: physical manifestation; suggest HP:0001597 Abnormality of the nail plus a more specific nail-bed term if available.
Nail plate distortion: sign in larger or longstanding subungual lesions; HP:0001597.
Gastric or visceral presentation: abdominal pain, gastrointestinal bleeding, anemia, or an incidental submucosal mass; site-specific evidence is predominantly small series and case reports.
Malignant disease: enlarging deep mass, local invasion, recurrence, or metastasis; highly variable and exceptionally rare.

Typical onset is in adolescence through middle adulthood, but pediatric and older-adult cases occur. Solitary digital disease is often reported more frequently in women, whereas extradigital lesions show less consistent sex bias. The disease is usually indolent until excision; symptoms may persist for years because of diagnostic delay.

4. Genetic and molecular information

MIR143–NOTCH alterations

MIR143–NOTCH1/2/3 fusions are recurrent somatic structural variants and probably the most characteristic known drivers. The available review states that they occur in nearly half of tumors, and another review explicitly records them in both benign and malignant lesions. (gaudio2022notchsignallingin pages 10-11, mertens2016genefusionsin pages 19-20)

Proposed consequence: juxtaposition of the active smooth-muscle/perivascular MIR143 regulatory region with a truncated NOTCH receptor drives ligand-independent or otherwise dysregulated NOTCH transcriptional output. This promotes survival and proliferation of glomus/pericytic-lineage cells. The causal chain is therefore:

somatic rearrangement → constitutive NOTCH signaling → altered perivascular-cell differentiation/proliferation → vascular-rich glomus-cell nodule → focal tenderness and cold-provoked pain.

Suggested annotations: NOTCH1, NOTCH2, NOTCH3, MIR143HG; GO:0007219 Notch signaling pathway; GO:0048514 blood-vessel morphogenesis; CL:0000669 pericyte.

Other alterations and differential molecular diagnoses

BRAF V600E defines a smaller MAPK-pathway subset. Testing may be informative in malignant, metastatic, histologically atypical, or diagnostically difficult tumors, although it is not required for routine classic digital lesions.

GLI1-rearranged or GLI1-amplified pericytic tumors may mimic glomus tumor. In a 2019 comparator series of ten GLI1-amplified tumors, all ten had GLI1 amplification, nine had CDK4 co-amplification, and eight had MDM2 co-amplification; four had at least 15 mitoses per ten high-power fields and three had necrosis. The authors concluded that amplification may provide an alternative mechanism of GLI1 activation in an emerging malignant soft-tissue-tumor group. DOI: 10.1038/s41379-019-0293-x, received February 18 and accepted May 1, 2019. These are differential-diagnosis data, not frequencies in conventional glomus tumor. (agaram2019gli1amplificationsexpandthe pages 2-4, agaram2019gli1amplificationsexpandthe pages 1-2)

No validated modifier gene, recurrent epigenetic class, germline carrier frequency, or protective allele has been established for sporadic solitary tumors. WGS/WES studies remain too small for dependable population-frequency inference.

5. Environmental information

No toxin, radiation exposure, pollution source, occupational exposure, lifestyle behavior, or infectious agent is recognized as causal. Glomus tumor is noncommunicable and noninfectious. Consequently, CTD-style chemical–disease causal annotations should not be added without direct experimental evidence. CHEBI annotations are relevant only to administered diagnostic agents or treatments, not etiology.

6. Mechanism and pathophysiology

Normal glomus bodies are specialized arteriovenous thermoregulatory structures in acral skin. Modified smooth-muscle glomus cells surround vascular channels and regulate blood flow. Neoplastic proliferation produces a compact, vascular-rich nodule in a confined and highly innervated space. Pressure, vascular tone changes, and cold-triggered contraction plausibly explain the disproportionate pain.

Upstream: MIR143–NOTCH rearrangement, less often MAPK activation such as BRAF V600E, or NF1-associated RAS pathway dysregulation.

Intermediate: abnormal NOTCH/RAS-MAPK signaling, perivascular-cell proliferation, and altered smooth-muscle differentiation. NOTCH has broad physiological roles in vascular genesis, remodeling, arterial–venous identity, branching, and homeostasis; therefore, its dysregulation is biologically coherent in a pericytic tumor. DOI: 10.1098/rsob.220004, published April 2022. (gaudio2022notchsignallingin pages 10-11)

Downstream: circumscribed tumor growth around vessels, local compression and stimulation of sensory fibers, severe tenderness, and cold-sensitive pain. Malignant progression adds high mitotic activity, atypical mitoses, genomic instability, invasion, and metastatic capability.

Suggested terms include CL:0000669 pericyte; GO:0007219 Notch signaling; GO:0000165 MAPK cascade; GO:0001525 angiogenesis; GO:0048514 blood-vessel morphogenesis; GO:0008283 cell population proliferation; GO:0006939 smooth-muscle contraction. Relevant cellular compartments include plasma membrane, cytoplasm, and nucleus for receptor cleavage and transcriptional signaling. No reproducible metabolomic, lipidomic, proteomic, single-cell, spatial-transcriptomic, or CRISPR-screen signature is presently established.

7. Anatomical structures affected

The prototypic sites are the distal fingers and toes, especially the subungual nail bed and fingertip pulp. Other cutaneous and deep-soft-tissue locations include forearm, arm, leg, trunk, head/neck, and peripheral nerve. Visceral tumors occur most characteristically in the gastric wall and more rarely in respiratory, genitourinary, bone, and other sites.

At tissue level, the lesion involves connective/soft tissue surrounding small vascular channels and comprises glomus cells with pericytic/smooth-muscle differentiation. Suggested mappings include CL:0000669 pericyte; UBERON:0002389 finger; UBERON:0000945 stomach; and current-release UBERON terms for nail bed, toe, skin, subcutaneous tissue, and vascular wall. Digital tumors are usually unilateral and solitary; multiplicity should prompt consideration of NF1 or glomuvenous malformation.

8. Temporal development

Onset is usually insidious. Small lesions may produce chronic intermittent or progressively intrusive pain for years without substantial growth. There is no accepted stage system for benign disease. A practical course classification is localized benign, incompletely excised/recurrent, uncertain malignant potential, and malignant/metastatic.

Following complete excision, pain often resolves promptly. Early postoperative persistence or rapid recurrence suggests residual tumor; late recurrence can represent regrowth or a second lesion. Malignant tumors have a variable course and may metastasize after a prolonged interval, so long-term surveillance is reasonable. No validated critical prevention window or spontaneous-remission pattern is known.

9. Inheritance and population

Robust population-based incidence and prevalence per 100,000 are unavailable. Frequently repeated proportions in narrative reviews derive from surgical pathology archives rather than population registries and should not be interpreted as prevalence.

Most solitary tumors are sporadic and nonfamilial. NF1 is autosomal dominant, with variable expressivity, and confers increased susceptibility to digital glomus tumors. The 2023 guideline specifically places digital glomus tumors among neoplasms whose risk increases in adults with NF1. (carton2023erngenturistumour pages 7-8)

Familial multiple glomuvenous malformation due to GLMN is autosomal dominant with incomplete penetrance and variable expression, but it is a related vascular-malformation disorder rather than a simple inheritance model for all glomus tumors. No genetic anticipation, consistent founder effect, consanguinity effect, germline mosaicism rate, or carrier frequency is established for conventional solitary glomus tumor. No convincing ethnic or geographic concentration is recognized.

10. Diagnostics

Clinical and imaging diagnosis

For a painful digital lesion, examination should document pinpoint tenderness, cold sensitivity, nail discoloration/deformity, and whether pressure or transient arterial occlusion changes pain. These bedside maneuvers can localize disease but do not replace pathology.

High-resolution ultrasonography may show a small hypoechoic hypervascular nodule. MRI typically shows a sharply defined lesion with low/intermediate T1 signal, high T2 signal, and strong enhancement, but very small tumors can be missed. Plain radiographs are usually normal, although longstanding subungual lesions may erode the distal phalanx.

Pathology

Definitive diagnosis is histopathologic. Typical lesions contain uniform round cells with sharply defined borders surrounding branching vessels. Variants include solid glomus tumor, glomangioma with a larger vascular component, and glomangiomyoma with spindle-cell/smooth-muscle maturation.

The expected immunophenotype is strong smooth-muscle actin and often h-caldesmon, calponin, vimentin, collagen IV, and laminin; desmin is variable. Cytokeratin, S100/SOX10, CD34, and endothelial markers are generally absent in tumor cells, though vessels label with CD31/ERG. Molecular confirmation by RNA sequencing, fusion panel, or NOTCH break-apart testing is most useful for atypical, deep, malignant, or diagnostically ambiguous lesions.

Differential diagnosis

Hemangioma/venous malformation: vascular spaces dominate; endothelial cells rather than perivascular glomus cells constitute the lesion.
Blue nevus/melanoma: melanocytic markers S100, SOX10, and melan-A support melanocytic lineage.
Schwannoma/neuroma: neural morphology and diffuse S100/SOX10.
Leiomyoma/angioleiomyoma: intersecting fascicles of spindle smooth-muscle cells rather than rounded glomus cells.
Myopericytoma/myofibroma: concentric vessel-associated myoid growth or biphasic morphology.
GIST in stomach: KIT/DOG1 expression and KIT/PDGFRA molecular alterations.
Neuroendocrine tumor: keratin and neuroendocrine-marker expression.
Paraganglioma: neuroendocrine chief cells with sustentacular S100/SOX10; fundamentally different entity.
GLI1-altered pericytic tumor: molecular GLI1 alteration, often S100 positivity and malignant morphology; the 2019 series shows why molecular analysis can prevent misclassification. (agaram2019gli1amplificationsexpandthe pages 2-4, agaram2019gli1amplificationsexpandthe pages 1-2)

Routine WES/WGS, CMA, karyotyping, mitochondrial testing, repeat-expansion analysis, liquid biopsy, and population screening are not indicated. For multiple digital tumors, syndromic features, or family history, evaluate NF1 clinically and consider appropriate germline testing; consider GLMN testing for multiple glomuvenous lesions.

11. Outcome and prognosis

Localized benign tumors have an excellent prognosis and ordinarily do not affect life expectancy. Complete excision is usually curative. Morbidity before diagnosis is dominated by pain, sleep interruption, impaired hand use, reduced occupational function, and repeated ineffective treatment. Recurrence is mainly associated with incomplete excision, multifocal disease, or an initially missed satellite lesion.

Malignant glomus tumor is rare but can recur and metastasize, particularly to lung, liver, bone, and soft tissue. Histologic concern rises with marked nuclear atypia, atypical mitoses, high mitotic activity, and deep/large tumors, but modern WHO practice emphasizes cytologic atypia and atypical mitotic figures more than size/depth alone. No reliable 5- or 10-year survival estimate can be given because reported cohorts are very small and heterogeneous. Molecular markers such as BRAF or NOTCH fusion have not yet been validated as independent prognostic biomarkers.

12. Treatment

Localized disease

Complete surgical excision with preservation of the nail matrix, neurovascular structures, or involved organ is standard. A transungual approach gives direct access to central subungual lesions; lateral or periungual approaches may reduce nail-matrix injury for appropriately located tumors. Gastric lesions are generally treated by wedge/partial gastrectomy or selected endoscopic full-thickness techniques after multidisciplinary review. Suggested NCIT terms: Surgical Excision, Local Tumor Excision, Partial Gastrectomy, and Endoscopic Resection.

Analgesics and avoidance of cold may provide temporary symptomatic relief but do not eradicate the tumor. Rehabilitation is rarely required except after extensive surgery or prolonged functional avoidance.

Malignant or unresectable disease

Management should occur in a sarcoma multidisciplinary center. Resectable disease is treated surgically, sometimes with radiotherapy for local-control indications. There is no glomus-tumor-specific standard chemotherapy regimen; anthracycline-based soft-tissue-sarcoma therapy, pazopanib, or other agents may be considered case by case, with limited evidence.

Molecularly selected targeted therapy is investigational. NCT03422679 evaluated oral CB-103, a pan-NOTCH pathway inhibitor, in a phase I/IIA open-label basket study. Eligibility explicitly included surgically unresectable, locally advanced, or metastatic malignant glomus tumor after systemic therapy, or another cancer with a confirmed NOTCH1–4 activating lesion. The study enrolled 79 participants overall, used 28-day cycles, and assessed dose-limiting toxicity and objective response. It was terminated for a business reason, not because the registry established inefficacy; results were posted January 16, 2024. ClinicalTrials.gov NCT03422679. (NCT03422679 chunk 1, NCT03422679 chunk 2)

The linked phase I publication is Hanna et al., Cancer Research Communications, September 14, 2023, PMID 37712875, DOI: 10.1158/2767-9764.CRC-23-0333. The available registry does not provide a glomus-tumor-specific response rate; basket-level outcomes must not be attributed to this rare subgroup. (NCT03422679 chunk 2)

There is no established pharmacogenomic dosing guideline, approved gene/cell/RNA therapy, or proven checkpoint inhibitor strategy.

13. Prevention

No primary prevention, vaccine, prophylactic medication, or environmental intervention is available. Population, newborn, and carrier screening are not recommended.

Secondary prevention consists of early recognition and complete removal of symptomatic lesions. Individuals with NF1 should be educated to report focal digital pain, cold sensitivity, or nail changes. The ERN GENTURIS guideline recommends broad adult NF1 clinical assessment at least every three years and identifies digital glomus tumor as an adult risk, although it does not recommend routine imaging specifically for asymptomatic digits. (carton2023erngenturistumour pages 7-8)

Tertiary prevention includes complete excision, pathology review of atypical lesions, re-excision when margins are clinically concerning, and surveillance for malignant or recurrent disease. Genetic counseling is appropriate for NF1 or suspected GLMN-associated familial disease.

14. Other species and natural disease

Sporadic glomus-cell tumors have been reported rarely in companion animals, including cats and dogs, but available evidence consists primarily of isolated pathology reports. No breed predisposition, incidence, zoonotic potential, transmission pathway, or validated cross-species susceptibility estimate is established. Human NOTCH, NF1, BRAF, and GLMN pathways are evolutionarily conserved, but conservation alone does not establish an equivalent animal syndrome.

Suggested taxa for future curation are Homo sapiens, NCBI Taxon 9606; Canis lupus familiaris, 9615; Felis catus, 9685; Mus musculus, 10090. Veterinary cases are noninfectious and have no zoonotic significance.

15. Model organisms

No widely adopted disease-specific genetically engineered mouse, rat, zebrafish, organoid, or patient-derived xenograft model was identified. Existing mechanistic interpretation relies mainly on human tumor sequencing and general vascular-NOTCH models. The vascular review establishes that NOTCH regulates vessel development, branching, identity, and homeostasis, but these experiments are pathway models rather than faithful glomus-tumor models. (gaudio2022notchsignallingin pages 10-11)

Priority models would include conditional expression of a MIR143–NOTCH fusion in mural-cell lineages such as PDGFRB-, CSPG4-, or ACTA2-expressing cells, NF1 loss in the same compartment, and patient-derived cultures or xenografts from malignant disease. Required validation should include perivascular rounded-cell morphology, SMA/h-caldesmon expression, vascular architecture, pain-related innervation, metastatic behavior where applicable, and reversibility with NOTCH inhibition.

Current understanding and key gaps

The contemporary model is that glomus tumor is a usually benign pericytic neoplasm in which recurrent MIR143–NOTCH fusions—reported in almost 50%—provide the clearest molecular driver, with NF1 representing the best-established inherited susceptibility context. (gaudio2022notchsignallingin pages 10-11, mertens2016genefusionsin pages 19-20, carton2023erngenturistumour pages 7-8) Clinical practice remains dominated by recognition and complete excision. The main 2023–2024 translational development was molecular selection of malignant glomus tumors for NOTCH inhibition, although no subgroup efficacy estimate or approved targeted therapy has emerged. (NCT03422679 chunk 1, NCT03422679 chunk 2)

High-priority gaps are population-based epidemiology, standardized HPO frequencies and quality-of-life measures, prospective recurrence and survival cohorts, harmonized malignant-risk criteria, validated prognostic biomarkers, single-cell/spatial profiling, and disease-specific experimental models. Ontology curation should preserve the boundary between soft-tissue glomus tumor, GLMN-associated glomuvenous malformation, and head-and-neck paraganglioma.

References

(NCT03422679 chunk 1): Study of CB-103 in Adult Patients With Advanced or Metastatic Solid Tumours and Haematological Malignancies. Cellestia Biotech AG. 2017. ClinicalTrials.gov Identifier: NCT03422679
(NCT03422679 chunk 2): Study of CB-103 in Adult Patients With Advanced or Metastatic Solid Tumours and Haematological Malignancies. Cellestia Biotech AG. 2017. ClinicalTrials.gov Identifier: NCT03422679
(gaudio2022notchsignallingin pages 10-11): Francesca Del Gaudio, Dongli Liu, and Urban Lendahl. Notch signalling in healthy and diseased vasculature. Open Biology, Apr 2022. URL: https://doi.org/10.1098/rsob.220004, doi:10.1098/rsob.220004. This article has 68 citations and is from a peer-reviewed journal.
(carton2023erngenturistumour pages 7-8): Charlotte Carton, D. Gareth Evans, Ignacio Blanco, Reinhard E. Friedrich, Rosalie E. Ferner, Said Farschtschi, Hector Salvador, Amedeo A. Azizi, Victor Mautner, Claas Röhl, Sirkku Peltonen, Stavros Stivaros, Eric Legius, Rianne Oostenbrink, Joan Brunet, Frank Van Calenbergh, Catherine Cassiman, Thomas Czech, María José Gavarrete de León, Henk Giele, Susie Henley, Conxi Lazaro, Vera Lipkovskaya, Eamonn R. Maher, Vanessa Martin, Irene Mathijssen, Enrico Opocher, Ana Elisabete Pires, Thomas Pletschko, Eirene Poupaki, Vita Ridola, Andre Rietman, Thorsten Rosenbaum, Alastair Santhouse, Astrid Sehested, Ian Simmons, Walter Taal, and Anja Wagner. Ern genturis tumour surveillance guidelines for individuals with neurofibromatosis type 1. eClinicalMedicine, 56:101818, Feb 2023. URL: https://doi.org/10.1016/j.eclinm.2022.101818, doi:10.1016/j.eclinm.2022.101818. This article has 123 citations and is from a peer-reviewed journal.
(agaram2019gli1amplificationsexpandthe pages 1-2): Narasimhan P. Agaram, Lei Zhang, Yun-Shao Sung, Samuel Singer, Todd Stevens, Carlos N. Prieto-Granada, Justin A. Bishop, Benjamin A. Wood, David Swanson, Brendan C. Dickson, and Cristina R. Antonescu. Gli1-amplifications expand the spectrum of soft tissue neoplasms defined by gli1 gene fusions. Modern Pathology, 32:1617-1626, Nov 2019. URL: https://doi.org/10.1038/s41379-019-0293-x, doi:10.1038/s41379-019-0293-x. This article has 117 citations and is from a domain leading peer-reviewed journal.
(mertens2016genefusionsin pages 19-20): Fredrik Mertens, Cristina R. Antonescu, and Felix Mitelman. Gene fusions in soft tissue tumors: recurrent and overlapping pathogenetic themes. Genes, 55:291-310, Apr 2016. URL: https://doi.org/10.1002/gcc.22335, doi:10.1002/gcc.22335. This article has 165 citations.
(agaram2019gli1amplificationsexpandthe pages 2-4): Narasimhan P. Agaram, Lei Zhang, Yun-Shao Sung, Samuel Singer, Todd Stevens, Carlos N. Prieto-Granada, Justin A. Bishop, Benjamin A. Wood, David Swanson, Brendan C. Dickson, and Cristina R. Antonescu. Gli1-amplifications expand the spectrum of soft tissue neoplasms defined by gli1 gene fusions. Modern Pathology, 32:1617-1626, Nov 2019. URL: https://doi.org/10.1038/s41379-019-0293-x, doi:10.1038/s41379-019-0293-x. This article has 117 citations and is from a domain leading peer-reviewed journal.

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Glomus Tumor: Disease Characteristics Research Report

1. Disease information

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