Ainhum

MONDO:0007074 Pathograph 14 Show in embeddings browser Dermatologic Disease Musculoskeletal Disease

Ainhum (dactylolysis spontanea) is a rare, acquired, progressive, and idiopathic constriction disorder that classically affects the fifth toe. A plantar groove or fissure becomes a circumferential fibrotic band, followed by distal enlargement, pain, soft-tissue and phalangeal resorption, and sometimes spontaneous autoamputation. True ainhum is distinguished from pseudo-ainhum, in which a hereditary disorder, vascular disease, congenital band, foreign-body tourniquet, or another identifiable cause produces an ainhum-like constriction.

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5
Pathophys.
2
Histopath.
7
Phenotypes
2
Hypotheses
2
Gaps
14
Pathograph
2
Medical Actions
3
Differentials
11
References
2
Deep Research
◈

Mechanistic Hypotheses

2
Progressive Constriction Model
progressive_constriction_model CANONICAL
Evidence balance 1 support
This descriptive natural-history model links a plantar fifth-toe groove or fissure to circumferential constriction, distal enlargement, progressive soft-tissue and phalangeal destruction, and eventual autoamputation. It describes the observed sequence without assigning an established initiating molecular cause.
Pathograph links
Toe-Base Groove or Fissure -> Circumferential Fibrotic Constriction DIRECT The groove extends around the toe to form the defining circumferential constriction.
Toe-Base Groove or Fissure -> Skin Fissure DIRECT The early groove can present clinically as chronic fissuring at the toe base.
Toe-Base Groove or Fissure -> Skin Ulcer UNKNOWN Foot ulceration may accompany the constricting lesion, although the clinical evidence does not resolve a single direct route from the groove to ulcer formation.
Circumferential Fibrotic Constriction -> Distal Bulbous Enlargement and Edema DIRECT Tissue distal to the constriction enlarges and becomes edematous as the ring progresses.
Circumferential Fibrotic Constriction -> Soft-Tissue, Ligament, and Phalangeal Destruction INDIRECT UNKNOWN INTERMEDIATES Progressive constriction is followed by absorption of underlying soft-tissue and skeletal structures. The intervening mechanical, inflammatory, perfusion, and remodeling steps remain incompletely resolved.
Circumferential Fibrotic Constriction -> Digital Constriction Ring DIRECT The fibrotic annular band is the structural basis of the digital constriction-ring phenotype.
Circumferential Fibrotic Constriction -> Foot Pain UNKNOWN Severe pain accompanies the constricting lesion, but the available case evidence does not distinguish contributions from pressure, inflammation, ischemia, or joint disruption.
Distal Bulbous Enlargement and Edema -> Edema DIRECT Distal volume increase in the radiographic staging model is attributed to lymphedema.
Soft-Tissue, Ligament, and Phalangeal Destruction -> Osteolytic Defects of Distal Toe Phalanges DIRECT Increased phalangeal resorption produces the characteristic distal-toe osteolytic defect.
Soft-Tissue, Ligament, and Phalangeal Destruction -> Autoamputation of Digits INDIRECT KNOWN INTERMEDIATES Structural absorption culminates in joint separation and spontaneous loss of the distal toe. Joint separation and hypermobility are represented as known omitted intermediates rather than separate graph nodes. Intermediates: Progressive bone narrowing and resorption; Joint separation and hypermobility
Show evidence (1 reference)
PMID:17924881 SUPPORT Human Clinical
"Eventually, the groove extends to encircle the toe, the underlying structures are absorbed and the toe autoamputates."
The case report and clinical review state the characteristic sequence from encircling groove through tissue absorption to autoamputation.
Mechanical-Inflammatory Wound-Repair Model
mechanical_inflammatory_wound_repair_model ALTERNATIVE
Evidence balance 2 support
Histopathologic observations support a candidate mechanical-inflammatory wound-repair process involving hyperkeratosis, chronic dermatitis, fibroblast-rich repair, and lymphocytic inflammation. These findings do not establish whether inflammation and repair initiate the band or arise secondarily after chronic constriction.
Pathograph links
Epidermal and Dermal Wound-Repair Response -> Circumferential Fibrotic Constriction UNKNOWN Mechanical-inflammatory repair may contribute to band formation, but available histology cannot determine directionality or directness.
Show evidence (2 references)
PMID:3214498 SUPPORT Human Clinical
"Among the usually considered etiopathogenetic hypotheses, our findings are in favor of a mechanical and inflammatory origin."
A seven-case histopathology series favored this interpretation, but did not experimentally establish the initiating cause.
PMID:2423578 SUPPORT Human Clinical
"Hyperkeratosis and parakeratosis, together with elongation of the epidermal rete pegs and acanthosis, are observed and these findings are associated with the presence of numerous fibroblasts and wound repair phenomena."
Surgical pathology directly documents fibroblast-rich wound-repair changes but does not determine whether they are primary or reactive.
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Discussions and Knowledge Gaps

2
Does the mechanical-inflammatory wound-repair pattern initiate the constriction band, or is it a secondary response to an earlier unidentified lesion?
KNOWLEDGE GAP OPEN ainhum_unresolved_initiating_cause
Attached to
pathophysiology#Toe-Base Groove or Fissure pathophysiology#Epidermal and Dermal Wound-Repair Response pathophysiology#Circumferential Fibrotic Constriction
Human pathology establishes hyperkeratosis, fibroblast-rich repair, lymphocytic inflammation, ligament destruction, and bone resorption, but cross-sectional tissue cannot determine temporal order or causal direction. Trauma, infection, neuropathy, perfusion change, and immune mechanisms therefore remain unproven as causes of true ainhum.
Show evidence (2 references)
PMID:3214498 SUPPORT Human Clinical
"It is a tropical disease of the adult, the origin of which remains obscure."
The seven-case pathology series explicitly states that the origin remains obscure.
PMID:2423578 SUPPORT Human Clinical
"The spontaneous amputation of the fifth toe, designated as dactylolysis spontanea, has no known etiology"
The surgical-pathology report also states that the etiology was unknown.
Is the reported association between true ainhum and an African acral keratoderma spectrum causal, a shared susceptibility, or an ascertainment association?
INTERPRETATION OPEN ainhum_acral_keratoderma_boundary
Attached to
pathophysiology#Epidermal and Dermal Wound-Repair Response
A 42-patient retrospective keratoderma cohort included only three patients with ainhum. Familial aggregation across the broader mixed-keratoderma cohort does not establish Mendelian inheritance or a causal gene for true ainhum, so no gene is encoded in this entry.
Show evidence (2 references)
PMID:36424301 SUPPORT Human Clinical
"3 had ainhum"
Only three members of the 42-patient acral-keratoderma cohort had ainhum.
PMID:36424301 SUPPORT Human Clinical
"A genetic origin is suggested by the familial aggregation of cases."
The authors suggest a genetic origin for the broader acral-keratoderma entity; this does not establish a gene or inheritance model for true ainhum.
⚙

Pathophysiology

5
Toe-Base Groove or Fissure
A groove or fissure develops at the plantar or medial base of the affected toe, classically pedal digit five. This is the earliest clinically described lesion; its initiating cause remains unknown.
Progressive Constriction Model
pedal digit 5 UBERON:0003635 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in pedal digit 5 (UBERON:0003635). UBERON:0003635 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Circumferential Fibrotic Constriction The groove extends around the toe to form the defining circumferential constriction. Progressive Constriction Model
Skin Fissure The early groove can present clinically as chronic fissuring at the toe base. Progressive Constriction Model
Skin Ulcer Foot ulceration may accompany the constricting lesion, although the clinical evidence does not resolve a single direct route from the groove to ulcer formation. Progressive Constriction Model
Show evidence (2 references)
PMID:17924881 SUPPORT Human Clinical
"a groove or fissure of constricting tissue forms around the proximal end of the fifth toe."
The clinical description identifies the proximal fifth-toe groove or fissure as the initial visible lesion.
PMID:26379327 SUPPORT Human Clinical
"development of a deep sulcus along the medial aspect"
The radiographic phase description independently localizes the early sulcus to the medial aspect of the toe.
Epidermal and Dermal Wound-Repair Response
Resected tissue can show epidermal hyperkeratotic change, numerous fibroblasts, wound-repair phenomena, chronic dermatitis, and a T-lymphocyte-predominant infiltrate. The response is modeled as an alternative candidate input because the evidence does not establish whether it precedes or follows mechanical constriction.
Mechanical-Inflammatory Wound-Repair Model
fibroblast CL:0000057 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology. T cell CL:0000084 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves T cell (CL:0000084). CL:0000084 is a cell type from the Cell Ontology.
wound healing GO:0042060 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal wound healing (GO:0042060). GO:0042060 is a biological process from the Gene Ontology. ⚠ ABNORMAL inflammatory response GO:0006954 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology. ↑ INCREASED
skin epidermis UBERON:0001003 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in skin epidermis (UBERON:0001003). UBERON:0001003 is an anatomical location from the Uberon multi-species anatomy ontology. dermis UBERON:0002067 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in dermis (UBERON:0002067). UBERON:0002067 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Circumferential Fibrotic Constriction Mechanical-inflammatory repair may contribute to band formation, but available histology cannot determine directionality or directness. Mechanical-Inflammatory Wound-Repair Model
Show evidence (2 references)
PMID:2423578 SUPPORT Human Clinical
"Hyperkeratosis and parakeratosis, together with elongation of the epidermal rete pegs and acanthosis, are observed and these findings are associated with the presence of numerous fibroblasts and wound repair phenomena."
Surgical histopathology supports epidermal change and a fibroblast-rich repair response.
PMID:2423578 SUPPORT Human Clinical
"The leukocytic infiltrate is identified as being principally of T lymphocyte type, suggesting the existence of an unknown immunologic response."
The tissue infiltrate was T-lymphocyte predominant, while the authors explicitly left its immunologic meaning unknown.
Circumferential Fibrotic Constriction
A hard annular fibrotic band surrounds the toe base and progressively constricts the enclosed soft tissues. This is the defining structural lesion of true ainhum.
Progressive Constriction Model
extracellular matrix organization GO:0030198 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal extracellular matrix organization (GO:0030198). GO:0030198 is a biological process from the Gene Ontology. ⚠ ABNORMAL
pedal digit 5 UBERON:0003635 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in pedal digit 5 (UBERON:0003635). UBERON:0003635 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Distal Bulbous Enlargement and Edema Tissue distal to the constriction enlarges and becomes edematous as the ring progresses. Progressive Constriction Model
Soft-Tissue, Ligament, and Phalangeal Destruction Progressive constriction is followed by absorption of underlying soft-tissue and skeletal structures. The intervening mechanical, inflammatory, perfusion, and remodeling steps remain incompletely resolved. Progressive Constriction Model
Digital Constriction Ring The fibrotic annular band is the structural basis of the digital constriction-ring phenotype. Progressive Constriction Model
Foot Pain Severe pain accompanies the constricting lesion, but the available case evidence does not distinguish contributions from pressure, inflammation, ischemia, or joint disruption. Progressive Constriction Model
Show evidence (1 reference)
PMID:26379327 SUPPORT Human Clinical
"The main DS feature of this condition is the development of a fibrotic constriction ring involving the base of one or more toes, conditioning eversion and absorption of distal structures, possibly progressing to spontaneous amputation"
The radiology review identifies a fibrotic constriction ring as the main lesion and links it to distal structural change.
Distal Bulbous Enlargement and Edema
The portion of the toe distal to the band becomes globular or enlarged; the radiographic phase model attributes this distal volume increase to lymphedema.
Progressive Constriction Model
pedal digit 5 UBERON:0003635 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in pedal digit 5 (UBERON:0003635). UBERON:0003635 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Edema Distal volume increase in the radiographic staging model is attributed to lymphedema. Progressive Constriction Model
Show evidence (2 references)
PMID:31401977 SUPPORT Human Clinical
"The toe becomes globular distal to the groove, associated with bone resorption and arterial narrowing"
The clinical stage description directly records globular enlargement distal to the groove.
PMID:31401977 SUPPORT Human Clinical
"The distal aspect of the toe was bulbous and oedematous."
Direct examination documented combined distal bulbous enlargement and edema in the affected toe.
Soft-Tissue, Ligament, and Phalangeal Destruction
Advanced disease includes absorption of underlying soft tissues, cortical bone resorption, complete ligament destruction, joint separation, and progressive loss of phalangeal structure.
Progressive Constriction Model
bone resorption GO:0045453 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased bone resorption (GO:0045453). GO:0045453 is a biological process from the Gene Ontology. ↑ INCREASED
pedal digit 5 UBERON:0003635 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in pedal digit 5 (UBERON:0003635). UBERON:0003635 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Osteolytic Defects of Distal Toe Phalanges Increased phalangeal resorption produces the characteristic distal-toe osteolytic defect. Progressive Constriction Model
Autoamputation of Digits Structural absorption culminates in joint separation and spontaneous loss of the distal toe. Joint separation and hypermobility are represented as known omitted intermediates rather than separate graph nodes. Progressive Constriction Model
Show evidence (2 references)
PMID:3214498 SUPPORT Human Clinical
"Classical features have been found, including hyperkeratosis, chronic dermatitis, osteoporosis with cortical bone resorption."
The seven-case pathology series directly documents cortical bone resorption.
PMID:3214498 SUPPORT Human Clinical
"This study has also revealed in all cases complete ligamental destruction."
Complete ligament destruction was observed in all seven histologically studied cases.
✶

Histopathology

2
Hyperkeratosis
Resected ainhum tissue can show hyperkeratosis with parakeratosis, acanthosis, and elongation of epidermal rete pegs.
Show evidence (1 reference)
PMID:2423578 SUPPORT Human Clinical
"Hyperkeratosis and parakeratosis, together with elongation of the epidermal rete pegs and acanthosis, are observed"
Surgical pathology directly documents these epidermal findings.
Lymphocytic Infiltrate
A leukocytic infiltrate dominated by T lymphocytes was reported, but its causal and immunologic significance remains unknown.
Show evidence (1 reference)
PMID:2423578 SUPPORT Human Clinical
"The leukocytic infiltrate is identified as being principally of T lymphocyte type, suggesting the existence of an unknown immunologic response."
The cellular composition is directly reported while the source itself qualifies its meaning as unknown.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Ainhum Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

7
Integument 1
Skin Ulcer HP:0200042 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Skin ulcer (HP:0200042). HP:0200042 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:17924881 SUPPORT Human Clinical
"It may present as chronic fissuring at the base of the fifth toe or as foot ulceration."
Foot ulceration is explicitly reported as a presentation.
Limbs 1
Autoamputation of Digits HP:0007460 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Autoamputation of digits (HP:0007460), qualified as located in pedal digit. HP:0007460 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:17924881 SUPPORT Human Clinical
"Eventually, the groove extends to encircle the toe, the underlying structures are absorbed and the toe autoamputates."
The report directly describes spontaneous autoamputation after structural absorption.
Metabolism 1
Edema HP:0000969 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Edema (HP:0000969), qualified as located in pedal digit. HP:0000969 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"The distal aspect of the toe was bulbous and oedematous."
Direct clinical examination documented a bulbous, edematous distal toe.
Prenatal and Birth 1
Digital Constriction Ring HP:0010491 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Digital constriction ring (HP:0010491). HP:0010491 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:12500788 SUPPORT Human Clinical
"Soft-tissue constriction was the most frequently presented radiological sign on the initial screening."
The radiographic series identifies soft-tissue constriction as the most frequent initial imaging sign in its selected sample.
Other 3
Skin Fissure HP:0031057 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Skin fissure (HP:0031057). HP:0031057 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:17924881 SUPPORT Human Clinical
"It may present as chronic fissuring at the base of the fifth toe or as foot ulceration."
Chronic fissuring is explicitly reported as a presentation.
Foot Pain HP:0025238 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Foot pain (HP:0025238). HP:0025238 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:25624138 SUPPORT Human Clinical
"They had consulted a dermatologist for violent pain in the fifth toe, which frequently prevented sleep"
Severe fifth-toe pain prompted consultation in the three-case series.
Osteolytic Defects of Distal Toe Phalanges Osteolytic defects of the distal phalanges of the toes HP:0010189 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Osteolytic defects of the distal phalanges of the toes (HP:0010189). HP:0010189 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"Findings on x-ray imaging include a radiolucent ring constricting the base of the toe, bone resorption or osteolysis is seen in the distal and middle phalanges, with a characteristic tapering effect"
The review section describes the characteristic phalangeal radiographic defect.
💊

Medical Actions

2
Early Constriction-Band Release With Z-Plasty
Category: Therapeutic Action: Reconstructive SurgeryNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Reconstructive Surgery (NCIT:C25351). NCIT:C25351 is a clinical intervention from the NCI Thesaurus. NCIT:C25351
At an early, structurally salvageable stage, excision or release of the circular constriction followed by Z-plasty can relieve pain and may prevent progression to amputation. Evidence is limited to case reports and series; no controlled efficacy evidence establishes an optimal technique.
Mechanism Target:
INHIBITS Circumferential Fibrotic Constriction — Z-plasty releases the circular band, directly reducing the defining mechanical constriction.
Show evidence (1 reference)
PMID:25624138 SUPPORT Human Clinical
"Once the diagnosis had been made, relief was promptly provided for all three patients through Z-plasty to remove the circular constriction around the toe in question."
The three-case series directly links Z-plasty to removal of the constriction and prompt symptom relief.
Show evidence (1 reference)
PMID:25624138 SUPPORT Human Clinical
"Once the diagnosis had been made, relief was promptly provided for all three patients through Z-plasty to remove the circular constriction around the toe in question."
Prompt relief after Z-plasty was reported in three patients.
Advanced-Stage Surgical Amputation or Disarticulation
Category: Therapeutic Action: surgical procedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is surgical procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. Ontology label: Surgical Procedure NCIT:C15329
When the toe is irreversibly destroyed, separated, hypermobile, or severely painful, surgical amputation or disarticulation may provide symptom relief and controlled wound closure. This late-stage palliative procedure is distinct from early band release.
Mechanism Target:
INHIBITS Foot Pain — Removal of an irreversibly damaged, painful toe is intended to alleviate advanced-stage pain rather than reverse the upstream disease mechanism.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"Timely amputation helps in pain relief"
The review section describes pain relief as an intended benefit of timely amputation.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"She was managed surgically by excision of the band, disarticulated at right fifth metatarsophalangeal joint and skin closure."
The case directly documents band excision, disarticulation, and closure in advanced disease.
🔬

Diagnosis

2
Clinical Assessment for True Ainhum
Diagnosis is primarily clinical: identify the acquired fifth-toe constriction and characteristic distal changes, establish spontaneous onset, and take a careful history for trauma, tourniquet, congenital band, hereditary keratoderma, vascular disease, infection, or another secondary cause that would favor pseudo-ainhum.
clinical assessment NCIT:C124351 NCI Thesaurus (NCIT)
Results: Hallmark annular constriction at the fifth-toe base with no identified precipitating or underlying cause supports true ainhum.
Show evidence (2 references)
PMID:27011582 SUPPORT Human Clinical
"Ainhum is an acquired progressive condition presenting with a constriction ring around the fifth toe."
The case report supports recognition of the characteristic acquired constriction-ring presentation.
PMID:27011582 SUPPORT Human Clinical
"It needs to be differentiated from pseudo ainhum, which may have a precipitating factor, and careful history may reveal a preventable cause."
The report explicitly supports searching for a precipitating cause to distinguish pseudo-ainhum.
Foot Radiography for Diagnosis and Staging
Plain radiographs evaluate the constriction ring, soft-tissue contour, phalangeal tapering, osteolysis, and stage. Imaging supports but does not replace the clinical distinction between idiopathic true ainhum and secondary pseudo-ainhum.
radiograph imaging procedure NCIT:C38101 NCI Thesaurus (NCIT)
Results: A soft-tissue constriction or radiolucent ring with progressive middle and distal phalangeal resorption supports ainhum and helps assign stage.
Show evidence (1 reference)
PMID:12500788 SUPPORT Human Clinical
"Early diagnosis and accurate staging of ainhum are facilitated by radiological examination of the feet."
The selected radiographic series supports foot radiography for diagnosis and staging.
🩻

Imaging Findings

2
Circumferential Soft-Tissue Constriction on Foot Radiograph
Plain radiography may show a radiolucent circumferential ring or focal soft-tissue constriction at the fifth-toe base.
Xray Diagnostic
Digital constriction ring HP:0010491 Human Phenotype Ontology (HP) pedal digit 5 UBERON:0003635 Uberon multi-species anatomy ontology (UBERON) Digital constriction ring HP:0010491 Human Phenotype Ontology (HP)
Show evidence (1 reference)
PMID:12500788 SUPPORT Human Clinical
"Soft-tissue constriction was the most frequently presented radiological sign on the initial screening."
The selected radiograph series directly supports this imaging finding.
Phalangeal Resorption and Tapering on Foot Radiograph
Advanced radiographs may show resorption or osteolysis of distal and middle phalanges with characteristic tapering.
Xray Diagnostic
Osteolytic defects of the distal phalanges of the toes HP:0010189 Human Phenotype Ontology (HP) pedal digit 5 UBERON:0003635 Uberon multi-species anatomy ontology (UBERON) Osteolytic defects of the distal phalanges of the toes HP:0010189 Human Phenotype Ontology (HP)
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"Findings on x-ray imaging include a radiolucent ring constricting the base of the toe, bone resorption or osteolysis is seen in the distal and middle phalanges, with a characteristic tapering effect"
The review section directly describes phalangeal osteolysis and tapering on x-ray.
📈

Progression

4
Stage 1 - Groove and Annular Fissure
A plantar clavus or groove progresses to an annular fissure around the toe. This is a descriptive clinical stage, not a precisely timed longitudinal interval.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"A clavus develops, which progresses to an annular fissure around the toe"
The review section describes the first clinical stage.
Stage 2 - Distal Enlargement and Bone Resorption
The toe becomes globular distal to the groove as structural resorption begins.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"The toe becomes globular distal to the groove, associated with bone resorption and arterial narrowing"
The review section describes the second clinical stage.
Stage 3 - Joint Separation and Hypermobility
Progressive bone loss permits painful separation at the joint and hypermobility of the distal toe.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"The very painful bone separates at the joint with hypermobility of the toe"
The review section describes the third clinical stage.
Stage 4 - Autoamputation
End-stage structural loss culminates in spontaneous autoamputation.
Show evidence (1 reference)
PMID:31401977 SUPPORT Human Clinical
"A bloodless auto-amputation of the toe with severe pains."
The review section describes the fourth clinical stage.
📊

Prevalence

1
Selected foot-radiograph cohort in Chicago, 1977-1999
Unknown Unknown
The study found 102 diagnoses among 6,000 reviewed foot radiographs in a mainly African American clinical imaging cohort. This selected, retrospectively screened sample is not a population-prevalence denominator, so no normalized prevalence rate is asserted.
Show evidence (2 references)
PMID:12500788 SUPPORT Human Clinical
"Between 1977 and 1999, a total 6000 radiographic studies of the feet were reviewed in a mainly African American population in Chicago, Illinois."
This defines the selected imaging sample and study interval.
PMID:12500788 SUPPORT Human Clinical
"After reviewing the complementary exams, 102 patients were diagnosed with dactylolysis spontanea or ainhum."
This records the study's case count without interpreting it as general population prevalence.
🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Ainhum:

Pseudo-Ainhum
Overlapping Features Pseudo-ainhum is an ainhum-like annular digital constriction secondary to an identifiable hereditary or acquired condition. The visible ring can closely resemble true ainhum, but causal history, associated systemic or cutaneous findings, congenital onset, or a foreign-body tourniquet favors the secondary diagnosis.
Distinguishing Features
  • An identifiable precipitating factor or underlying disorder.
  • Congenital onset, non-classic distribution, or syndromic skin findings.
  • Management must address the underlying cause as well as the constriction.
Show evidence (2 references)
PMID:25657437 SUPPORT Human Clinical
"Pseudoainhum is a similar condition that occurs as a secondary event resulting from certain hereditary and nonhereditary diseases that lead to annular constriction of digits."
The report defines pseudo-ainhum by a secondary hereditary or nonhereditary cause.
PMID:27011582 SUPPORT Human Clinical
"It needs to be differentiated from pseudo ainhum, which may have a precipitating factor, and careful history may reveal a preventable cause."
A careful causal history is identified as a key discriminator.
Keratoderma Hereditarium Mutilans (Vohwinkel Syndrome) MONDO:0007422
Overlapping Features Vohwinkel syndrome is an inherited mutilating palmoplantar keratoderma that can produce ainhumoid constriction bands. Keratoderma and a hereditary syndromic pattern support Vohwinkel syndrome rather than idiopathic true ainhum.
Distinguishing Features
  • Hereditary palmoplantar keratoderma and other syndrome-associated skin findings.
  • Ainhumoid bands are secondary to the inherited keratoderma.
Show evidence (1 reference)
PMID:25624138 SUPPORT Human Clinical
"ainhumoid palmoplantar keratoderma, which is of genetic origin and occurs for instance in Vohwinkel syndrome."
The series distinguishes genetic ainhumoid keratoderma from true ainhum and names Vohwinkel syndrome as an example.
Ischemia-Associated Pseudo-Ainhum
Overlapping Features Peripheral arterial disease can coexist with an ainhum-like toe constriction and should be classified as secondary pseudo-ainhum rather than used as evidence that ischemia causes true ainhum.
Distinguishing Features
  • Objective chronic lower-limb ischemia or peripheral arterial disease.
  • Management includes assessment of perfusion and possible revascularization.
Show evidence (1 reference)
PMID:21693445 SUPPORT Human Clinical
"We report a case of pseudoainhum in a Caucasian female with underlying chronic lower limb peripheral arterial disease (PAD)."
This Ainhum-specific case identifies PAD-associated constriction as pseudo-ainhum, not true ainhum.
{ }

Source YAML

click to show 
name: Ainhum
creation_date: "2026-02-04T17:27:57Z"
description: >-
  Ainhum (dactylolysis spontanea) is a rare, acquired, progressive, and
  idiopathic constriction disorder that classically affects the fifth toe. A
  plantar groove or fissure becomes a circumferential fibrotic band, followed
  by distal enlargement, pain, soft-tissue and phalangeal resorption, and
  sometimes spontaneous autoamputation. True ainhum is distinguished from
  pseudo-ainhum, in which a hereditary disorder, vascular disease, congenital
  band, foreign-body tourniquet, or another identifiable cause produces an
  ainhum-like constriction.
categories:
- Dermatologic Disease
- Musculoskeletal Disease
- Rare Disease
synonyms:
- Dactylolysis spontanea
- Spontaneous dactylolysis
disease_term:
  preferred_term: ainhum
  term:
    id: MONDO:0007074
    label: ainhum
parents:
- Dermatologic Disease
- Musculoskeletal Disease
mechanistic_hypotheses:
- hypothesis_group_id: progressive_constriction_model
  hypothesis_label: Progressive Constriction Model
  status: CANONICAL
  description: >-
    This descriptive natural-history model links a plantar fifth-toe groove or
    fissure to circumferential constriction, distal enlargement, progressive
    soft-tissue and phalangeal destruction, and eventual autoamputation. It
    describes the observed sequence without assigning an established initiating
    molecular cause.
  evidence:
  - reference: PMID:17924881
    reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Eventually, the groove extends to encircle the toe, the underlying
      structures are absorbed and the toe autoamputates.
    explanation: >-
      The case report and clinical review state the characteristic sequence
      from encircling groove through tissue absorption to autoamputation.
- hypothesis_group_id: mechanical_inflammatory_wound_repair_model
  hypothesis_label: Mechanical-Inflammatory Wound-Repair Model
  status: ALTERNATIVE
  description: >-
    Histopathologic observations support a candidate mechanical-inflammatory
    wound-repair process involving hyperkeratosis, chronic dermatitis,
    fibroblast-rich repair, and lymphocytic inflammation. These findings do not
    establish whether inflammation and repair initiate the band or arise
    secondarily after chronic constriction.
  evidence:
  - reference: PMID:3214498
    reference_title: "[Spontaneous dactylolysis or ainhum. Histopathologic study]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among the usually considered etiopathogenetic hypotheses, our findings
      are in favor of a mechanical and inflammatory origin.
    explanation: >-
      A seven-case histopathology series favored this interpretation, but did
      not experimentally establish the initiating cause.
  - reference: PMID:2423578
    reference_title: "The surgical pathology of ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hyperkeratosis and parakeratosis, together with elongation of the
      epidermal rete pegs and acanthosis, are observed and these findings are
      associated with the presence of numerous fibroblasts and wound repair
      phenomena.
    explanation: >-
      Surgical pathology directly documents fibroblast-rich wound-repair
      changes but does not determine whether they are primary or reactive.
pathophysiology:
- name: Toe-Base Groove or Fissure
  description: >-
    A groove or fissure develops at the plantar or medial base of the affected
    toe, classically pedal digit five. This is the earliest clinically described
    lesion; its initiating cause remains unknown.
  locations:
  - preferred_term: pedal digit 5
    term:
      id: UBERON:0003635
      label: pedal digit 5
  evidence:
  - reference: PMID:17924881
    reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a groove or fissure of constricting tissue forms around the proximal end
      of the fifth toe.
    explanation: >-
      The clinical description identifies the proximal fifth-toe groove or
      fissure as the initial visible lesion.
  - reference: PMID:26379327
    reference_title: "Dactylolysis spontanea (ainhum)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      development of a deep sulcus along the medial aspect
    explanation: >-
      The radiographic phase description independently localizes the early
      sulcus to the medial aspect of the toe.
  downstream:
  - target: Circumferential Fibrotic Constriction
    causal_link_type: DIRECT
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      The groove extends around the toe to form the defining circumferential
      constriction.
    evidence:
    - reference: PMID:17924881
      reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Eventually, the groove extends to encircle the toe, the underlying
        structures are absorbed and the toe autoamputates.
      explanation: >-
        The reported sequence directly connects extension of the groove with
        encirclement of the toe.
  - target: Skin Fissure
    causal_link_type: DIRECT
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      The early groove can present clinically as chronic fissuring at the toe
      base.
    evidence:
    - reference: PMID:17924881
      reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        It may present as chronic fissuring at the base of the fifth toe or as
        foot ulceration.
      explanation: >-
        Chronic fissuring is explicitly described as a presentation of ainhum.
  - target: Skin Ulcer
    causal_link_type: UNKNOWN
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      Foot ulceration may accompany the constricting lesion, although the
      clinical evidence does not resolve a single direct route from the groove
      to ulcer formation.
    evidence:
    - reference: PMID:17924881
      reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        It may present as chronic fissuring at the base of the fifth toe or as
        foot ulceration.
      explanation: >-
        The report establishes ulceration as a presentation while leaving edge
        directness unresolved.
- name: Epidermal and Dermal Wound-Repair Response
  description: >-
    Resected tissue can show epidermal hyperkeratotic change, numerous
    fibroblasts, wound-repair phenomena, chronic dermatitis, and a
    T-lymphocyte-predominant infiltrate. The response is modeled as an
    alternative candidate input because the evidence does not establish whether
    it precedes or follows mechanical constriction.
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  locations:
  - preferred_term: skin epidermis
    term:
      id: UBERON:0001003
      label: skin epidermis
  - preferred_term: dermis
    term:
      id: UBERON:0002067
      label: dermis
  biological_processes:
  - preferred_term: wound healing
    modifier: ABNORMAL
    term:
      id: GO:0042060
      label: wound healing
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  evidence:
  - reference: PMID:2423578
    reference_title: "The surgical pathology of ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hyperkeratosis and parakeratosis, together with elongation of the
      epidermal rete pegs and acanthosis, are observed and these findings are
      associated with the presence of numerous fibroblasts and wound repair
      phenomena.
    explanation: >-
      Surgical histopathology supports epidermal change and a fibroblast-rich
      repair response.
  - reference: PMID:2423578
    reference_title: "The surgical pathology of ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The leukocytic infiltrate is identified as being principally of T
      lymphocyte type, suggesting the existence of an unknown immunologic
      response.
    explanation: >-
      The tissue infiltrate was T-lymphocyte predominant, while the authors
      explicitly left its immunologic meaning unknown.
  downstream:
  - target: Circumferential Fibrotic Constriction
    causal_link_type: UNKNOWN
    hypothesis_groups:
    - mechanical_inflammatory_wound_repair_model
    description: >-
      Mechanical-inflammatory repair may contribute to band formation, but
      available histology cannot determine directionality or directness.
    evidence:
    - reference: PMID:3214498
      reference_title: "[Spontaneous dactylolysis or ainhum. Histopathologic study]."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Among the usually considered etiopathogenetic hypotheses, our findings
        are in favor of a mechanical and inflammatory origin.
      explanation: >-
        The seven-case series supports the hypothesis but does not prove a
        causal direction from inflammation to constriction.
- name: Circumferential Fibrotic Constriction
  description: >-
    A hard annular fibrotic band surrounds the toe base and progressively
    constricts the enclosed soft tissues. This is the defining structural lesion
    of true ainhum.
  locations:
  - preferred_term: pedal digit 5
    term:
      id: UBERON:0003635
      label: pedal digit 5
  biological_processes:
  - preferred_term: extracellular matrix organization
    modifier: ABNORMAL
    term:
      id: GO:0030198
      label: extracellular matrix organization
  evidence:
  - reference: PMID:26379327
    reference_title: "Dactylolysis spontanea (ainhum)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The main DS feature of this condition is the development of a fibrotic
      constriction ring involving the base of one or more toes, conditioning
      eversion and absorption of distal structures, possibly progressing to
      spontaneous amputation
    explanation: >-
      The radiology review identifies a fibrotic constriction ring as the main
      lesion and links it to distal structural change.
  downstream:
  - target: Distal Bulbous Enlargement and Edema
    causal_link_type: DIRECT
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      Tissue distal to the constriction enlarges and becomes edematous as the
      ring progresses.
    evidence:
    - reference: PMID:31401977
      reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The toe becomes globular distal to the groove, associated with bone
        resorption and arterial narrowing
      explanation: >-
        The stage description directly places globular distal enlargement after
        development of the groove.
  - target: Soft-Tissue, Ligament, and Phalangeal Destruction
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      Progressive constriction is followed by absorption of underlying
      soft-tissue and skeletal structures. The intervening mechanical,
      inflammatory, perfusion, and remodeling steps remain incompletely
      resolved.
    evidence:
    - reference: PMID:17924881
      reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Eventually, the groove extends to encircle the toe, the underlying
        structures are absorbed and the toe autoamputates.
      explanation: >-
        The clinical sequence supports constriction preceding structural
        absorption, but not a direct molecular mechanism.
  - target: Digital Constriction Ring
    causal_link_type: DIRECT
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      The fibrotic annular band is the structural basis of the digital
      constriction-ring phenotype.
    evidence:
    - reference: PMID:12500788
      reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Soft-tissue constriction was the most frequently presented radiological
        sign on the initial screening.
      explanation: >-
        A selected radiographic series directly documents soft-tissue
        constriction as the predominant imaging sign.
  - target: Foot Pain
    causal_link_type: UNKNOWN
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      Severe pain accompanies the constricting lesion, but the available case
      evidence does not distinguish contributions from pressure, inflammation,
      ischemia, or joint disruption.
    evidence:
    - reference: PMID:25624138
      reference_title: "[Ainhum and \"African acral keratoderma\": three cases]."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        They had consulted a dermatologist for violent pain in the fifth toe,
        which frequently prevented sleep
      explanation: >-
        All three reported patients presented because of severe fifth-toe pain.
- name: Distal Bulbous Enlargement and Edema
  description: >-
    The portion of the toe distal to the band becomes globular or enlarged; the
    radiographic phase model attributes this distal volume increase to
    lymphedema.
  locations:
  - preferred_term: pedal digit 5
    term:
      id: UBERON:0003635
      label: pedal digit 5
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The toe becomes globular distal to the groove, associated with bone
      resorption and arterial narrowing
    explanation: >-
      The clinical stage description directly records globular enlargement
      distal to the groove.
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The distal aspect of the toe was bulbous and oedematous.
    explanation: >-
      Direct examination documented combined distal bulbous enlargement and
      edema in the affected toe.
  downstream:
  - target: Edema
    causal_link_type: DIRECT
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      Distal volume increase in the radiographic staging model is attributed to
      lymphedema.
    evidence:
    - reference: PMID:31401977
      reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The distal aspect of the toe was bulbous and oedematous.
      explanation: >-
        Direct clinical examination documented edema distal to the constriction.
- name: Soft-Tissue, Ligament, and Phalangeal Destruction
  description: >-
    Advanced disease includes absorption of underlying soft tissues, cortical
    bone resorption, complete ligament destruction, joint separation, and
    progressive loss of phalangeal structure.
  locations:
  - preferred_term: pedal digit 5
    term:
      id: UBERON:0003635
      label: pedal digit 5
  biological_processes:
  - preferred_term: bone resorption
    modifier: INCREASED
    term:
      id: GO:0045453
      label: bone resorption
  evidence:
  - reference: PMID:3214498
    reference_title: "[Spontaneous dactylolysis or ainhum. Histopathologic study]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Classical features have been found, including hyperkeratosis, chronic
      dermatitis, osteoporosis with cortical bone resorption.
    explanation: >-
      The seven-case pathology series directly documents cortical bone
      resorption.
  - reference: PMID:3214498
    reference_title: "[Spontaneous dactylolysis or ainhum. Histopathologic study]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This study has also revealed in all cases complete ligamental destruction.
    explanation: >-
      Complete ligament destruction was observed in all seven histologically
      studied cases.
  downstream:
  - target: Osteolytic Defects of Distal Toe Phalanges
    causal_link_type: DIRECT
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      Increased phalangeal resorption produces the characteristic distal-toe
      osteolytic defect.
    evidence:
    - reference: PMID:31401977
      reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Findings on x-ray imaging include a radiolucent ring constricting the
        base of the toe, bone resorption or osteolysis is seen in the distal and
        middle phalanges, with a characteristic tapering effect
      explanation: >-
        The review section directly links advanced ainhum to phalangeal
        resorption and osteolysis on radiography.
  - target: Autoamputation of Digits
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Progressive bone narrowing and resorption
    - Joint separation and hypermobility
    hypothesis_groups:
    - progressive_constriction_model
    description: >-
      Structural absorption culminates in joint separation and spontaneous
      loss of the distal toe. Joint separation and hypermobility are represented
      as known omitted intermediates rather than separate graph nodes.
    evidence:
    - reference: PMID:17924881
      reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Eventually, the groove extends to encircle the toe, the underlying
        structures are absorbed and the toe autoamputates.
      explanation: >-
        The clinical account directly places autoamputation after absorption of
        underlying structures.
phenotypes:
- name: Digital Constriction Ring
  category: Dermatologic
  description: >-
    A circumferential constriction ring surrounds the base of the affected toe.
  phenotype_term:
    preferred_term: Digital constriction ring
    term:
      id: HP:0010491
      label: Digital constriction ring
  evidence:
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Soft-tissue constriction was the most frequently presented radiological
      sign on the initial screening.
    explanation: >-
      The radiographic series identifies soft-tissue constriction as the most
      frequent initial imaging sign in its selected sample.
- name: Skin Fissure
  category: Dermatologic
  description: >-
    Chronic fissuring can occur at the base of the fifth toe.
  phenotype_term:
    preferred_term: Skin fissure
    term:
      id: HP:0031057
      label: Skin fissure
  evidence:
  - reference: PMID:17924881
    reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It may present as chronic fissuring at the base of the fifth toe or as
      foot ulceration.
    explanation: >-
      Chronic fissuring is explicitly reported as a presentation.
- name: Skin Ulcer
  category: Dermatologic
  description: >-
    The constricting lesion can present as foot ulceration.
  phenotype_term:
    preferred_term: Skin ulcer
    term:
      id: HP:0200042
      label: Skin ulcer
  evidence:
  - reference: PMID:17924881
    reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It may present as chronic fissuring at the base of the fifth toe or as
      foot ulceration.
    explanation: >-
      Foot ulceration is explicitly reported as a presentation.
- name: Foot Pain
  category: Musculoskeletal
  description: >-
    Pain may be severe, sleep-disrupting, and a major reason for presentation
    and surgical intervention.
  phenotype_term:
    preferred_term: Foot pain
    term:
      id: HP:0025238
      label: Foot pain
  evidence:
  - reference: PMID:25624138
    reference_title: "[Ainhum and \"African acral keratoderma\": three cases]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They had consulted a dermatologist for violent pain in the fifth toe,
      which frequently prevented sleep
    explanation: >-
      Severe fifth-toe pain prompted consultation in the three-case series.
- name: Edema
  category: Dermatologic
  description: >-
    Distal swelling is incorporated into the radiographic phase model and
    attributed to lymphedema.
  phenotype_term:
    preferred_term: Edema
    term:
      id: HP:0000969
      label: Edema
    located_in:
      preferred_term: pedal digit
      term:
        id: UBERON:0001466
        label: pedal digit
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The distal aspect of the toe was bulbous and oedematous.
    explanation: >-
      Direct clinical examination documented a bulbous, edematous distal toe.
- name: Osteolytic Defects of Distal Toe Phalanges
  category: Musculoskeletal
  description: >-
    Radiographs can show resorption and tapering of the distal and middle
    phalanges of the affected toe.
  phenotype_term:
    preferred_term: Osteolytic defects of the distal phalanges of the toes
    term:
      id: HP:0010189
      label: Osteolytic defects of the distal phalanges of the toes
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Findings on x-ray imaging include a radiolucent ring constricting the base
      of the toe, bone resorption or osteolysis is seen in the distal and middle
      phalanges, with a characteristic tapering effect
    explanation: >-
      The review section describes the characteristic phalangeal radiographic
      defect.
- name: Autoamputation of Digits
  category: Musculoskeletal
  description: >-
    End-stage structural destruction may culminate in spontaneous loss of the
    affected toe.
  phenotype_term:
    preferred_term: Autoamputation of digits
    term:
      id: HP:0007460
      label: Autoamputation of digits
    located_in:
      preferred_term: pedal digit
      term:
        id: UBERON:0001466
        label: pedal digit
  evidence:
  - reference: PMID:17924881
    reference_title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Eventually, the groove extends to encircle the toe, the underlying
      structures are absorbed and the toe autoamputates.
    explanation: >-
      The report directly describes spontaneous autoamputation after structural
      absorption.
histopathology:
- name: Hyperkeratosis
  finding_term:
    preferred_term: Hyperkeratosis
    term:
      id: NCIT:C35541
      label: Hyperkeratosis
  description: >-
    Resected ainhum tissue can show hyperkeratosis with parakeratosis,
    acanthosis, and elongation of epidermal rete pegs.
  evidence:
  - reference: PMID:2423578
    reference_title: "The surgical pathology of ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hyperkeratosis and parakeratosis, together with elongation of the
      epidermal rete pegs and acanthosis, are observed
    explanation: >-
      Surgical pathology directly documents these epidermal findings.
- name: Lymphocytic Infiltrate
  finding_term:
    preferred_term: Lymphocytic Infiltrate
    term:
      id: NCIT:C35983
      label: Lymphocytic Infiltrate
  description: >-
    A leukocytic infiltrate dominated by T lymphocytes was reported, but its
    causal and immunologic significance remains unknown.
  evidence:
  - reference: PMID:2423578
    reference_title: "The surgical pathology of ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The leukocytic infiltrate is identified as being principally of T
      lymphocyte type, suggesting the existence of an unknown immunologic
      response.
    explanation: >-
      The cellular composition is directly reported while the source itself
      qualifies its meaning as unknown.
imaging_findings:
- name: Circumferential Soft-Tissue Constriction on Foot Radiograph
  modality: XRAY
  imaging_finding_term:
    preferred_term: Digital constriction ring
    term:
      id: HP:0010491
      label: Digital constriction ring
  phenotype_term:
    preferred_term: Digital constriction ring
    term:
      id: HP:0010491
      label: Digital constriction ring
  located_in:
    preferred_term: pedal digit 5
    term:
      id: UBERON:0003635
      label: pedal digit 5
  diagnostic: true
  description: >-
    Plain radiography may show a radiolucent circumferential ring or focal
    soft-tissue constriction at the fifth-toe base.
  evidence:
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Soft-tissue constriction was the most frequently presented radiological
      sign on the initial screening.
    explanation: >-
      The selected radiograph series directly supports this imaging finding.
- name: Phalangeal Resorption and Tapering on Foot Radiograph
  modality: XRAY
  imaging_finding_term:
    preferred_term: Osteolytic defects of the distal phalanges of the toes
    term:
      id: HP:0010189
      label: Osteolytic defects of the distal phalanges of the toes
  phenotype_term:
    preferred_term: Osteolytic defects of the distal phalanges of the toes
    term:
      id: HP:0010189
      label: Osteolytic defects of the distal phalanges of the toes
  located_in:
    preferred_term: pedal digit 5
    term:
      id: UBERON:0003635
      label: pedal digit 5
  diagnostic: true
  description: >-
    Advanced radiographs may show resorption or osteolysis of distal and middle
    phalanges with characteristic tapering.
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Findings on x-ray imaging include a radiolucent ring constricting the base
      of the toe, bone resorption or osteolysis is seen in the distal and middle
      phalanges, with a characteristic tapering effect
    explanation: >-
      The review section directly describes phalangeal osteolysis and tapering
      on x-ray.
progression:
- phase: Stage 1 - Groove and Annular Fissure
  notes: >-
    A plantar clavus or groove progresses to an annular fissure around the toe.
    This is a descriptive clinical stage, not a precisely timed longitudinal
    interval.
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A clavus develops, which progresses to an annular fissure around the toe
    explanation: >-
      The review section describes the first clinical stage.
- phase: Stage 2 - Distal Enlargement and Bone Resorption
  notes: >-
    The toe becomes globular distal to the groove as structural resorption
    begins.
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The toe becomes globular distal to the groove, associated with bone
      resorption and arterial narrowing
    explanation: >-
      The review section describes the second clinical stage.
- phase: Stage 3 - Joint Separation and Hypermobility
  notes: >-
    Progressive bone loss permits painful separation at the joint and
    hypermobility of the distal toe.
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The very painful bone separates at the joint with hypermobility of the toe
    explanation: >-
      The review section describes the third clinical stage.
- phase: Stage 4 - Autoamputation
  notes: >-
    End-stage structural loss culminates in spontaneous autoamputation.
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A bloodless auto-amputation of the toe with severe pains.
    explanation: >-
      The review section describes the fourth clinical stage.
diagnosis:
- name: Clinical Assessment for True Ainhum
  description: >-
    Diagnosis is primarily clinical: identify the acquired fifth-toe
    constriction and characteristic distal changes, establish spontaneous onset,
    and take a careful history for trauma, tourniquet, congenital band,
    hereditary keratoderma, vascular disease, infection, or another secondary
    cause that would favor pseudo-ainhum.
  diagnosis_term:
    preferred_term: clinical assessment
    term:
      id: NCIT:C124351
      label: Clinical Evaluation
  results: >-
    Hallmark annular constriction at the fifth-toe base with no identified
    precipitating or underlying cause supports true ainhum.
  evidence:
  - reference: PMID:27011582
    reference_title: "Ainhum: A Spot Diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ainhum is an acquired progressive condition presenting with a
      constriction ring around the fifth toe.
    explanation: >-
      The case report supports recognition of the characteristic acquired
      constriction-ring presentation.
  - reference: PMID:27011582
    reference_title: "Ainhum: A Spot Diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It needs to be differentiated from pseudo ainhum, which may have a
      precipitating factor, and careful history may reveal a preventable cause.
    explanation: >-
      The report explicitly supports searching for a precipitating cause to
      distinguish pseudo-ainhum.
- name: Foot Radiography for Diagnosis and Staging
  description: >-
    Plain radiographs evaluate the constriction ring, soft-tissue contour,
    phalangeal tapering, osteolysis, and stage. Imaging supports but does not
    replace the clinical distinction between idiopathic true ainhum and
    secondary pseudo-ainhum.
  diagnosis_term:
    preferred_term: radiograph imaging procedure
    term:
      id: NCIT:C38101
      label: X-Ray Imaging
  results: >-
    A soft-tissue constriction or radiolucent ring with progressive middle and
    distal phalangeal resorption supports ainhum and helps assign stage.
  evidence:
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Early diagnosis and accurate staging of ainhum are facilitated by
      radiological examination of the feet.
    explanation: >-
      The selected radiographic series supports foot radiography for diagnosis
      and staging.
prevalence:
- population: Selected foot-radiograph cohort in Chicago, 1977-1999
  measure_type: UNKNOWN
  prevalence_class: UNKNOWN
  notes: >-
    The study found 102 diagnoses among 6,000 reviewed foot radiographs in a
    mainly African American clinical imaging cohort. This selected,
    retrospectively screened sample is not a population-prevalence denominator,
    so no normalized prevalence rate is asserted.
  evidence:
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Between 1977 and 1999, a total 6000 radiographic studies of the feet were
      reviewed in a mainly African American population in Chicago, Illinois.
    explanation: >-
      This defines the selected imaging sample and study interval.
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      After reviewing the complementary exams, 102 patients were diagnosed with
      dactylolysis spontanea or ainhum.
    explanation: >-
      This records the study's case count without interpreting it as general
      population prevalence.
biochemical: []
genetic: []
environmental: []
treatments:
- name: Early Constriction-Band Release With Z-Plasty
  action_category: THERAPEUTIC
  description: >-
    At an early, structurally salvageable stage, excision or release of the
    circular constriction followed by Z-plasty can relieve pain and may prevent
    progression to amputation. Evidence is limited to case reports and series;
    no controlled efficacy evidence establishes an optimal technique.
  treatment_term:
    preferred_term: Reconstructive Surgery
    term:
      id: NCIT:C25351
      label: Reconstructive Surgery
  target_mechanisms:
  - target: Circumferential Fibrotic Constriction
    treatment_effect: INHIBITS
    description: >-
      Z-plasty releases the circular band, directly reducing the defining
      mechanical constriction.
    evidence:
    - reference: PMID:25624138
      reference_title: "[Ainhum and \"African acral keratoderma\": three cases]."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Once the diagnosis had been made, relief was promptly provided for all
        three patients through Z-plasty to remove the circular constriction
        around the toe in question.
      explanation: >-
        The three-case series directly links Z-plasty to removal of the
        constriction and prompt symptom relief.
  evidence:
  - reference: PMID:25624138
    reference_title: "[Ainhum and \"African acral keratoderma\": three cases]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Once the diagnosis had been made, relief was promptly provided for all
      three patients through Z-plasty to remove the circular constriction around
      the toe in question.
    explanation: >-
      Prompt relief after Z-plasty was reported in three patients.
- name: Advanced-Stage Surgical Amputation or Disarticulation
  action_category: THERAPEUTIC
  description: >-
    When the toe is irreversibly destroyed, separated, hypermobile, or severely
    painful, surgical amputation or disarticulation may provide symptom relief
    and controlled wound closure. This late-stage palliative procedure is
    distinct from early band release.
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Foot Pain
    treatment_effect: INHIBITS
    description: >-
      Removal of an irreversibly damaged, painful toe is intended to alleviate
      advanced-stage pain rather than reverse the upstream disease mechanism.
    evidence:
    - reference: PMID:31401977
      reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Timely amputation helps in pain relief
      explanation: >-
        The review section describes pain relief as an intended benefit of
        timely amputation.
  evidence:
  - reference: PMID:31401977
    reference_title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      She was managed surgically by excision of the band, disarticulated at
      right fifth metatarsophalangeal joint and skin closure.
    explanation: >-
      The case directly documents band excision, disarticulation, and closure in
      advanced disease.
datasets: []
differential_diagnoses:
- name: Pseudo-Ainhum
  description: >-
    Pseudo-ainhum is an ainhum-like annular digital constriction secondary to an
    identifiable hereditary or acquired condition. The visible ring can closely
    resemble true ainhum, but causal history, associated systemic or cutaneous
    findings, congenital onset, or a foreign-body tourniquet favors the
    secondary diagnosis.
  distinguishing_features:
  - An identifiable precipitating factor or underlying disorder.
  - Congenital onset, non-classic distribution, or syndromic skin findings.
  - Management must address the underlying cause as well as the constriction.
  evidence:
  - reference: PMID:25657437
    reference_title: "Familial ainhum: a case report of multiple toe involvement in a father and son, staging of ainhum with insight into different types of constricting bands."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pseudoainhum is a similar condition that occurs as a secondary event
      resulting from certain hereditary and nonhereditary diseases that lead to
      annular constriction of digits.
    explanation: >-
      The report defines pseudo-ainhum by a secondary hereditary or
      nonhereditary cause.
  - reference: PMID:27011582
    reference_title: "Ainhum: A Spot Diagnosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It needs to be differentiated from pseudo ainhum, which may have a
      precipitating factor, and careful history may reveal a preventable cause.
    explanation: >-
      A careful causal history is identified as a key discriminator.
- name: Keratoderma Hereditarium Mutilans (Vohwinkel Syndrome)
  description: >-
    Vohwinkel syndrome is an inherited mutilating palmoplantar keratoderma that
    can produce ainhumoid constriction bands. Keratoderma and a hereditary
    syndromic pattern support Vohwinkel syndrome rather than idiopathic true
    ainhum.
  disease_term:
    preferred_term: Vohwinkel syndrome
    term:
      id: MONDO:0007422
      label: keratoderma hereditarium mutilans
  distinguishing_features:
  - Hereditary palmoplantar keratoderma and other syndrome-associated skin findings.
  - Ainhumoid bands are secondary to the inherited keratoderma.
  evidence:
  - reference: PMID:25624138
    reference_title: "[Ainhum and \"African acral keratoderma\": three cases]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ainhumoid palmoplantar keratoderma, which is of genetic origin and occurs
      for instance in Vohwinkel syndrome.
    explanation: >-
      The series distinguishes genetic ainhumoid keratoderma from true ainhum
      and names Vohwinkel syndrome as an example.
- name: Ischemia-Associated Pseudo-Ainhum
  description: >-
    Peripheral arterial disease can coexist with an ainhum-like toe
    constriction and should be classified as secondary pseudo-ainhum rather than
    used as evidence that ischemia causes true ainhum.
  distinguishing_features:
  - Objective chronic lower-limb ischemia or peripheral arterial disease.
  - Management includes assessment of perfusion and possible revascularization.
  evidence:
  - reference: PMID:21693445
    reference_title: "Pseudoainhum of the toe with underlying chronic lower-limb ischemia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a case of pseudoainhum in a Caucasian female with underlying
      chronic lower limb peripheral arterial disease (PAD).
    explanation: >-
      This Ainhum-specific case identifies PAD-associated constriction as
      pseudo-ainhum, not true ainhum.
discussions:
- discussion_id: ainhum_unresolved_initiating_cause
  prompt: >-
    Does the mechanical-inflammatory wound-repair pattern initiate the
    constriction band, or is it a secondary response to an earlier unidentified
    lesion?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Toe-Base Groove or Fissure
  - pathophysiology#Epidermal and Dermal Wound-Repair Response
  - pathophysiology#Circumferential Fibrotic Constriction
  rationale: >-
    Human pathology establishes hyperkeratosis, fibroblast-rich repair,
    lymphocytic inflammation, ligament destruction, and bone resorption, but
    cross-sectional tissue cannot determine temporal order or causal
    direction. Trauma, infection, neuropathy, perfusion change, and immune
    mechanisms therefore remain unproven as causes of true ainhum.
  evidence:
  - reference: PMID:3214498
    reference_title: "[Spontaneous dactylolysis or ainhum. Histopathologic study]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It is a tropical disease of the adult, the origin of which remains
      obscure.
    explanation: >-
      The seven-case pathology series explicitly states that the origin remains
      obscure.
  - reference: PMID:2423578
    reference_title: "The surgical pathology of ainhum (dactylolysis spontanea)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The spontaneous amputation of the fifth toe, designated as dactylolysis
      spontanea, has no known etiology
    explanation: >-
      The surgical-pathology report also states that the etiology was unknown.
- discussion_id: ainhum_acral_keratoderma_boundary
  prompt: >-
    Is the reported association between true ainhum and an African acral
    keratoderma spectrum causal, a shared susceptibility, or an ascertainment
    association?
  kind: INTERPRETATION
  status: OPEN
  attaches_to:
  - pathophysiology#Epidermal and Dermal Wound-Repair Response
  rationale: >-
    A 42-patient retrospective keratoderma cohort included only three patients
    with ainhum. Familial aggregation across the broader mixed-keratoderma
    cohort does not establish Mendelian inheritance or a causal gene for true
    ainhum, so no gene is encoded in this entry.
  evidence:
  - reference: PMID:36424301
    reference_title: "\"African\" acral keratoderma: Further evidence for a single entity. A retrospective study of 42 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      3 had ainhum
    explanation: >-
      Only three members of the 42-patient acral-keratoderma cohort had ainhum.
  - reference: PMID:36424301
    reference_title: "\"African\" acral keratoderma: Further evidence for a single entity. A retrospective study of 42 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A genetic origin is suggested by the familial aggregation of cases.
    explanation: >-
      The authors suggest a genetic origin for the broader acral-keratoderma
      entity; this does not establish a gene or inheritance model for true
      ainhum.
references:
- reference: PMID:17924881
  title: "An unusual cause of ulceration: ainhum (dactylolysis spontanea)."
  findings: []
- reference: PMID:12500788
  title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
  findings: []
- reference: PMID:2423578
  title: "The surgical pathology of ainhum (dactylolysis spontanea)."
  findings: []
- reference: PMID:3214498
  title: "[Spontaneous dactylolysis or ainhum. Histopathologic study]."
  findings: []
- reference: PMID:26379327
  title: "Dactylolysis spontanea (ainhum)."
  findings: []
- reference: PMID:31401977
  title: "Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report."
  findings: []
- reference: PMID:25624138
  title: "[Ainhum and \"African acral keratoderma\": three cases]."
  findings: []
- reference: PMID:25657437
  title: "Familial ainhum: a case report of multiple toe involvement in a father and son, staging of ainhum with insight into different types of constricting bands."
  findings: []
- reference: PMID:27011582
  title: "Ainhum: A Spot Diagnosis."
  findings: []
- reference: PMID:21693445
  title: "Pseudoainhum of the toe with underlying chronic lower-limb ischemia."
  findings: []
- reference: PMID:36424301
  title: "\"African\" acral keratoderma: Further evidence for a single entity. A retrospective study of 42 patients."
  findings: []
notes: >-
  Re-reviewed on 2026-07-17. Curation keeps true ainhum idiopathic, separates
  observed progression from the alternative mechanical-inflammatory hypothesis,
  distinguishes pseudo-ainhum from the focal disorder, and treats the
  radiographic 102-of-6,000 result as selected-cohort ascertainment rather than
  population prevalence.
📚

References & Deep Research

References

11
PMID:17924881
An unusual cause of ulceration: ainhum (dactylolysis spontanea).
No top-level findings curated for this source.
PMID:12500788
Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients.
No top-level findings curated for this source.
PMID:2423578
The surgical pathology of ainhum (dactylolysis spontanea).
No top-level findings curated for this source.
PMID:3214498
[Spontaneous dactylolysis or ainhum. Histopathologic study].
No top-level findings curated for this source.
PMID:26379327
Dactylolysis spontanea (ainhum).
No top-level findings curated for this source.
PMID:31401977
Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report.
No top-level findings curated for this source.
PMID:25624138
[Ainhum and "African acral keratoderma": three cases].
No top-level findings curated for this source.
PMID:25657437
Familial ainhum: a case report of multiple toe involvement in a father and son, staging of ainhum with insight into different types of constricting bands.
No top-level findings curated for this source.
PMID:27011582
Ainhum: A Spot Diagnosis.
No top-level findings curated for this source.
PMID:21693445
Pseudoainhum of the toe with underlying chronic lower-limb ischemia.
No top-level findings curated for this source.
PMID:36424301
"African" acral keratoderma: Further evidence for a single entity. A retrospective study of 42 patients.
No top-level findings curated for this source.

Deep Research

2
Disorder ▸

Disorder

  • Name: Ainhum
  • Category: Complex
  • Existing deep-research providers: falcon
  • Existing evidence reference count in YAML: 25

Key Pathophysiology Nodes

  • Constricting groove forms around proximal toe
  • Progressive constriction encircles the toe
  • Absorption of underlying structures
  • Toe autoamputation
  • Deep research literature mapping

Citation Inventory (for evidence mapping)

  • DOI:10.1111/j.1742-481x.2007.00297.x
  • DOI:10.1177/2050313x231204197
  • DOI:10.1186/s12895-019-0092-6
Falcon ▸
Disease Pathophysiology Research Report
Edison Scientific Literature 13 citations 2026-02-04T11:42:35.147533

Disease Pathophysiology Research Report

Target Disease - Disease Name: Ainhum (dactylolysis spontanea) - MONDO ID: not available in retrieved sources - Category: Complex

Pathophysiology description Ainhum is an idiopathic, mutilating dermatological disorder characterized by a progressive constricting annular band that classically forms at the base of the fifth toe and deepens circumferentially to produce distal swelling, osteolysis, and eventual spontaneous, typically bloodless auto‑amputation. The annular band behaves as a fibrous scar “ligature,” whose contraction promotes localized anoxia/ischemia and necrosis while perpetuating chronic wound repair and dermal fibrosis. Histopathology described in case series and reviews includes marked epidermal hyperkeratosis and acanthosis adjacent to the band, with a dermal inflammatory infiltrate (lymphocytes, plasma cells) and increased fibroblasts within a collagenous, fibrotic band. Radiographs (when obtained) show a radiolucent constricting ring near the base of the affected toe with tapering and osteolysis of the distal phalanx. Ischemic contributions are supported by reports of “arterial narrowing” in intermediate stages, and some angiographic studies report distal plantar arch abnormalities, although peripheral pulses can remain palpable; a neuropathic component is suggested by early pain and by mechanical nerve compression within the tightening band. Distinguishing idiopathic ainhum from pseudo‑ainhum (constriction bands with identifiable causes) is critical: pseudo‑ainhum may arise from congenital bands, hereditary palmoplantar keratoderma (PPK) syndromes (notably connexin‑related), trauma, infections, or systemic connective tissue diseases. (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4, jemmott2007anunusualcause pages 4-4, tchouakam2019ainhumarare pages 1-3, govender2023palmoplantarkeratodermapseudoainhum pages 1-2)

Core Pathophysiology - Primary mechanisms: Progressive formation and contraction of a fibrosed collagen band at the base of the digit, acting as a constricting ligature; resultant local ischemia (anoxia) and tissue necrosis; chronic injury–repair cycle with dermal fibrosis; epidermal hyperproliferation and disordered differentiation adjacent to the band; distal osteolysis. (jemmott2007anunusualcause pages 2-4, tchouakam2019ainhumarare pages 3-4) - Dysregulated molecular/cellular pathways: Tissue fibrosis and extracellular matrix remodeling; inflammatory cell infiltration; keratinocyte differentiation/hyperkeratosis; ischemia/hypoxia responses in local tissues; mechanical compression of neurovascular structures. While idiopathic ainhum lacks a proven genetic driver, pseudo‑ainhum in hereditary PPK implicates gap junction biology (connexins) and disruption of epidermal calcium gradients that regulate keratinocyte differentiation. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, tchouakam2019ainhumarare pages 3-4) - Affected cellular processes: Keratinocyte proliferation and differentiation (hyperkeratosis, acanthosis); fibroblast activation and collagen deposition (fibrous band); endothelial/vascular tone and perfusion locally (ischemia/arterial narrowing); nociceptive signaling and nerve compression. (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4)

Key Molecular Players - Genes/Proteins (implicated primarily in pseudo‑ainhum associated with hereditary PPK rather than idiopathic ainhum): - GJB2 (Connexin 26), GJB4 (Connexin 30.3), GJB6 (Connexin 30), GJA1 (Connexin 43): connexin genes expressed in skin; mutations in connexin genes are linked to PPK with pseudo‑ainhum/annular constriction and related phenotypes (e.g., Vohwinkel, Bart–Pumphrey, KID syndromes), reflecting perturbed gap‑junction intercellular communication and epidermal differentiation. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, govender2023palmoplantarkeratodermapseudoainhum pages 7-8) - Chemical entities: Calcium ion (Ca2+)—connexin dysfunction can disrupt the epidermal calcium gradient that orchestrates keratinocyte differentiation; inflammatory mediators likely contribute but are not specifically delineated in idiopathic ainhum. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4) - Cell types: Keratinocytes (hyperkeratosis/acanthosis), dermal fibroblasts (fibrous collagen band), endothelial cells (arterial narrowing/ischemia), peripheral sensory neurons (pain/neuropathy hypothesis). (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4) - Anatomical locations: Plantar skin at the base of the fifth toe (most common site), epidermis/dermis of the affected digit, digital arteries. (tchouakam2019ainhumarare pages 1-3, tchouakam2019ainhumarare pages 3-4)

Biological Processes (GO-style annotation, mechanistically implicated) - Gap junction intercellular communication (connexin-related pseudo‑ainhum in PPK) and epidermal calcium homeostasis/keratinocyte differentiation. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4) - Dermal fibrosis and extracellular matrix organization at the constriction band; wound healing/inflammatory response. (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4) - Response to hypoxia/ischemia at the distal digit; osteolysis/bone resorption in advanced stages. (tchouakam2019ainhumarare pages 3-4)

Cellular Components - Epidermis (stratum corneum, stratum spinosum) with hyperkeratosis and acanthosis adjacent to the band; dermis with fibrosed collagen band and inflammatory infiltrate; periarterial regions/digital arteries implicated in ischemia; peripheral nerve bundles traversing the band. (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4)

Disease Progression The classic four-stage evolution (Cole/Browne framework) involves: stage 1—initial clavus/scaling fissure forming a shallow annular groove at the medial plantar base of the fifth toe; stage 2—deepening constricting band with a globular distal toe, ulceration, and “bone resorption and arterial narrowing”; stage 3—further compression with fracture/separation and hypermobility of the distal phalanx; stage 4—“a bloodless auto‑amputation.” These stages guide management, with earlier stages amenable to band excision/Z‑plasty and later stages often requiring amputation. (tchouakam2019ainhumarare pages 3-4, tchouakam2019ainhumarare pages 1-3, jemmott2007anunusualcause pages 4-4)

Phenotype–mechanism correlations - Constriction ring of the digit and distal bulbous swelling: correlates with a dermal collagenous fibrous band that contracts like scar tissue, acting as a ligature and promoting ischemia. (jemmott2007anunusualcause pages 2-4) - Plantar hyperkeratosis adjacent to the band: reflects keratinocyte hyperproliferation and disturbed differentiation; in pseudo‑ainhum with PPK, connexin defects further perturb epidermal homeostasis. (tchouakam2019ainhumarare pages 3-4, govender2023palmoplantarkeratodermapseudoainhum pages 2-4) - Osteolysis and tapering of distal phalanx: consequence of chronic ischemia and mechanical stress distal to the constriction. (tchouakam2019ainhumarare pages 3-4) - Pain and neuropathic complaints early in disease: may reflect nerve compression by the tightening band. (jemmott2007anunusualcause pages 2-4)

Distinction from pseudo‑ainhum Idiopathic ainhum is defined by spontaneous, idiopathic constriction, typically of the fifth toe in individuals of African descent, whereas pseudo‑ainhum denotes constriction bands secondary to identifiable causes: congenital bands (amniotic/Streeter), hereditary PPK and related genodermatoses (connexinopathies), trauma, infections (leprosy, mycoses, syphilis), inflammatory dermatoses (psoriasis), and connective tissue diseases (scleroderma, DLE). Pseudo‑ainhum is not restricted to the fifth toe and is more broadly distributed across digits and patient populations. (govender2023palmoplantarkeratodermapseudoainhum pages 1-2, jemmott2007anunusualcause pages 4-4)

Current applications and real‑world implementations - Diagnosis and staging: Clinical recognition of the annular groove and staging guide management. Plain radiography can show the radiolucent ring and osteolysis; vascular assessment may note arterial narrowing. (tchouakam2019ainhumarare pages 3-4, tchouakam2019ainhumarare pages 1-3) - Interventions: Early stages (1–2) may be managed with surgical band excision and Z‑plasty to relieve constriction; advanced stages (3–4) often require amputation. Some reports suggest that once bone is involved, band‑disrupting procedures may not halt progression, supporting timely intervention. (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 4-4) - Awareness in wound care: Underdiagnosis is noted; clinicians managing chronic toe ulcers in at‑risk populations should consider ainhum/pseudo‑ainhum in the differential. (jemmott2007anunusualcause pages 4-4)

Expert opinions and analysis - The fibrosed collagen band’s behavior “like a scar” that forms a ligature provides a coherent mechanistic link between histopathology (fibrosis), local ischemia/anoxia, and the stereotyped clinical evolution to auto‑amputation; this aligns with the observed benefit of early surgical release. (jemmott2007anunusualcause pages 2-4, tchouakam2019ainhumarare pages 3-4) - The idiopathic nature of ainhum contrasts with pseudo‑ainhum’s identifiable causes; in hereditary PPK‑associated pseudo‑ainhum, connexin mutations provide a molecular entry point (gap junction dysfunction and calcium‑dependent differentiation), but such molecular drivers are not established for idiopathic ainhum. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, govender2023palmoplantarkeratodermapseudoainhum pages 1-2)

Relevant statistics and data - Typical site and staging: Fifth toe is the most commonly affected digit, with a four‑stage natural history culminating in “bloodless auto‑amputation”; radiography shows a constricting radiolucent ring and distal osteolysis/tapering in advanced stages. (tchouakam2019ainhumarare pages 1-3, tchouakam2019ainhumarare pages 3-4) - Vascular findings: Reports include “arterial narrowing” at intermediate stages and angiographic distal plantar arch abnormalities in some patients, supporting an ischemia component despite sometimes normal pulses. (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4)

Ontology‑linked annotations and evidence table | Category | Entity (preferred label) | Ontology + ID | Role/Notes | Evidence | |---|---|---|---|---| | Gene/Protein | GJB2 (Connexin 26) | HGNC:GJB2 | Connexin gap-junction protein implicated in hereditary PPK / pseudo-ainhum mechanisms (disrupts intercellular communication) | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4), DOI: 10.1177/2050313x231204197, https://doi.org/10.1177/2050313x231204197 | | Gene/Protein | GJB4 (Connexin 30.3) | HGNC:GJB4 | Variant reported as VUS in PPK/pseudo-ainhum case; implicates connexin dysfunction in epidermal phenotype | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4), DOI: 10.1177/2050313x231204197, https://doi.org/10.1177/2050313x231204197 | | Gene/Protein | GJB6 (Connexin 30) | HGNC:GJB6 | Reported pathogenic variant (e.g., p.Gly59Arg) in connexin-related PPK with pseudo-ainhum features | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4), DOI: 10.1177/2050313x231204197, https://doi.org/10.1177/2050313x231204197 | | Gene/Protein | GJA1 (Connexin 43) | HGNC:GJA1 | Connexin expressed in skin; implicated broadly in epidermal gap-junction biology relevant to keratoderma syndromes | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4), DOI: 10.1177/2050313x231204197, https://doi.org/10.1177/2050313x231204197 | | Biological process | Gap junction intercellular communication | GO:Gap_junction_intercellular_communication | Core process by which connexins regulate epidermal homeostasis; dysfunction linked to hyperkeratosis/pseudo-ainhum | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4), DOI: 10.1177/2050313x231204197, https://doi.org/10.1177/2050313x231204197 | | Biological process | Keratinocyte differentiation | GO:Keratinocyte_differentiation | Altered differentiation (hyperkeratosis, acanthosis) observed in cases and associated with connexin defects | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, tchouakam2019ainhumarare pages 3-4), DOI: 10.1177/2050313x231204197; DOI: 10.1186/s12895-019-0092-6 | | Biological process | Epidermal calcium ion homeostasis | GO:Epidermal_calcium_ion_homeostasis | Connexin dysfunction can perturb the epidermal Ca2+ gradient, a regulator of keratinocyte maturation | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4), DOI: 10.1177/2050313x231204197, https://doi.org/10.1177/2050313x231204197 | | Biological process | Dermal fibrosis | GO:Dermal_fibrosis | Fibroblast-mediated fibrosis beneath constriction band contributes to progressive tightening and groove formation | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Biological process | Response to hypoxia / ischemia-related processes | GO:Response_to_hypoxia | Ischemia/vascular compromise proposed as a contributor to distal tissue loss and osteolysis | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Cell type | Keratinocyte | CL:Keratinocyte | Primary epidermal cell showing hyperkeratosis/acanthosis; central to PPK and pseudo-ainhum pathology | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, tchouakam2019ainhumarare pages 3-4), DOI: 10.1177/2050313x231204197; DOI: 10.1186/s12895-019-0092-6 | | Cell type | Fibroblast | CL:Fibroblast | Dermal fibroblasts form fibrous band and participate in chronic inflammation/fibrosis at constriction site | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Cell type | Endothelial cell | CL:Endothelial_cell | Vascular endothelium implicated in ischemia hypothesis; vascular compromise may drive distal changes | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Cell type | Peripheral sensory neuron | CL:Peripheral_sensory_neuron | Peripheral neuropathy proposed in some series as contributing factor to disease evolution | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Anatomical site | Fifth toe | UBERON:Fifth_toe | Classic and most commonly affected digit in idiopathic ainhum cases | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Anatomical site | Skin of foot (plantar skin) | UBERON:Skin_of_foot | Site of plantar hyperkeratosis and constriction-band formation in pseudo-ainhum/PPK-associated cases | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, tchouakam2019ainhumarare pages 3-4), DOI: 10.1177/2050313x231204197; DOI: 10.1186/s12895-019-0092-6 | | Anatomical site | Epidermis | UBERON:Epidermis | Epidermal changes reported (hyperkeratosis, acanthosis) adjacent to constriction | (govender2023palmoplantarkeratodermapseudoainhum pages 1-2, tchouakam2019ainhumarare pages 3-4), DOI: 10.1177/2050313x231204197; DOI: 10.1186/s12895-019-0092-6 | | Anatomical site | Dermis | UBERON:Dermis | Dermal lymphocytic infiltrate and fibrosis reported in histology of constriction bands | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Anatomical site | Digital arteries | UBERON:Digital_arteries | Vascular structures implicated by ischemia hypothesis for progressive distal tissue loss | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Chemical entity | Calcium ion (Ca2+) | CHEBI:Calcium_ion | Key regulator of keratinocyte differentiation; connexin disruption reported to affect epidermal Ca2+ gradient | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4), DOI: 10.1177/2050313x231204197, https://doi.org/10.1177/2050313x231204197 | | Phenotype | Constriction ring of digit | HPO:Constriction_ring_of_digit | Clinical hallmark (annular groove) that tightens and may progress to auto-amputation | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Phenotype | Plantar hyperkeratosis | HPO:Plantar_hyperkeratosis | Associated PPK phenotype seen in pseudo-ainhum and familial keratoderma cases | (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, tchouakam2019ainhumarare pages 3-4), DOI: 10.1177/2050313x231204197; DOI: 10.1186/s12895-019-0092-6 | | Phenotype | Auto-amputation of digit | HPO:Auto_amputation | End-stage outcome of progressive constriction band (documented in case series) | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 | | Phenotype | Osteolysis of phalanges | HPO:Osteolysis_of_phalanges | Radiographic finding (tapering/resorption) in advanced stages | (tchouakam2019ainhumarare pages 3-4), DOI: 10.1186/s12895-019-0092-6, https://doi.org/10.1186/s12895-019-0092-6 |

Table: Table mapping key genes, processes, cells, anatomical sites, chemicals and phenotypes for Ainhum (dactylolysis spontanea) to ontology labels with concise roles and primary evidence (context IDs and DOIs). This supports structured annotation and citation for a disease knowledge base.

Evidence quotes for key claims

"a bloodless auto-amputation" (tchouakam2019ainhumarare pages 3-4) "thickening of the stratum corneum near the fibrous band, hyper-keratosis or acanthosis of the epidermis and the presence of lymphocytes and fibroblasts in the dermis" (tchouakam2019ainhumarare pages 3-4) "fibrosed collagen band contracts like a scar, forming a ligature that causes localised anoxia and necrosis" (jemmott2007anunusualcause pages 2-4) "bone resorption and arterial narrowing" (tchouakam2019ainhumarare pages 3-4) "distinguishes ainhum (idiopathic, classically affecting the fifth toe) from pseudo-ainhum (constriction bands with identifiable causes)" (govender2023palmoplantarkeratodermapseudoainhum pages 1-2)

Blockquote: Verbatim, citable excerpts from retrieved sources summarizing staging (auto-amputation), histopathology (hyperkeratosis, inflammatory infiltrate, fibroblast/fibrosis), ischemic/osteolytic findings, and the clinical distinction between ainhum and pseudo-ainhum; useful as direct evidence for a pathophysiology report.

Structured Annotations - Genes/Proteins (HGNC): GJB2; GJB4; GJB6; GJA1 (implicated in pseudo‑ainhum due to PPK). (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, govender2023palmoplantarkeratodermapseudoainhum pages 7-8) - Biological processes (GO): gap junction intercellular communication; keratinocyte differentiation; epidermal calcium ion homeostasis; dermal fibrosis; response to hypoxia. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4) - Cell types (CL): keratinocyte; fibroblast; endothelial cell; peripheral sensory neuron. (tchouakam2019ainhumarare pages 3-4, jemmott2007anunusualcause pages 2-4) - Anatomical locations (UBERON): fifth toe; skin of foot; epidermis; dermis; digital arteries. (tchouakam2019ainhumarare pages 1-3, tchouakam2019ainhumarare pages 3-4) - Chemical entities (CHEBI): calcium ion. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4) - Phenotypes (HPO): constriction ring of digit; plantar hyperkeratosis; auto‑amputation; osteolysis of phalanges. (tchouakam2019ainhumarare pages 3-4)

Evidence items with PMIDs/DOIs/URLs and publication dates - Govender KC, Pillay S. Palmoplantar keratoderma, pseudo‑ainhum and knuckle pads in an African patient: A case report. SAGE Open Medical Case Reports. 2023 Jan; doi:10.1177/2050313x231204197. URL: https://doi.org/10.1177/2050313x231204197 (supports pseudo‑ainhum vs ainhum distinction; connexin biology; keratinocyte differentiation and epidermal calcium gradient disruption) (govender2023palmoplantarkeratodermapseudoainhum pages 7-8, govender2023palmoplantarkeratodermapseudoainhum pages 2-4, govender2023palmoplantarkeratodermapseudoainhum pages 1-2) - Tchouakam DN, Tochie JN, Guifo ML, Choukem SP. Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report. BMC Dermatology. 2019 Aug; doi:10.1186/s12895-019-0092-6. URL: https://doi.org/10.1186/s12895-019-0092-6 (supports staging, imaging features, histopathology summary, proposed etiologies including ischemia/neuropathy/trauma/infection/genetic keratoderma) (tchouakam2019ainhumarare pages 3-4, tchouakam2019ainhumarare pages 1-3) - Jemmott T, Foster AV, Edmonds ME. An unusual cause of ulceration: ainhum (dactylolysis spontanea). International Wound Journal. 2007 Sep;4:251–254. doi:10.1111/j.1742-481x.2007.00297.x. URL: https://doi.org/10.1111/j.1742-481x.2007.00297.x (supports fibrosed collagen band behaving like a scar ligature; histopathology details; neuropathy/ischemia considerations; treatment implications and underdiagnosis emphasis) (jemmott2007anunusualcause pages 2-4, jemmott2007anunusualcause pages 4-4)

Limitations and open questions - Idiopathic ainhum currently lacks a defined molecular driver; most molecular insights derive from pseudo‑ainhum in hereditary PPK (connexinopathies). Prospective histopathology with molecular profiling (fibrosis, ECM, neurovascular changes) would clarify mechanisms and therapeutic targets. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4, jemmott2007anunusualcause pages 2-4)

References: context IDs are provided inline; URLs and DOIs included above for accessibility.

References

  1. (govender2023palmoplantarkeratodermapseudoainhum pages 7-8): Kellicia Courtney Govender and Somasundram Pillay. Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an african patient: a case report. SAGE Open Medical Case Reports, Jan 2023. URL: https://doi.org/10.1177/2050313x231204197, doi:10.1177/2050313x231204197. This article has 3 citations and is from a peer-reviewed journal.

  2. (tchouakam2019ainhumarare pages 3-4): Diego Nitcheu Tchouakam, Joel Noutakdie Tochie, Marc Leroy Guifo, and Simeon Pierre Choukem. Ainhum, a rare mutilating dermatological disease in a female cameroonian: a case report. BMC Dermatology, Aug 2019. URL: https://doi.org/10.1186/s12895-019-0092-6, doi:10.1186/s12895-019-0092-6. This article has 16 citations and is from a peer-reviewed journal.

  3. (govender2023palmoplantarkeratodermapseudoainhum pages 2-4): Kellicia Courtney Govender and Somasundram Pillay. Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an african patient: a case report. SAGE Open Medical Case Reports, Jan 2023. URL: https://doi.org/10.1177/2050313x231204197, doi:10.1177/2050313x231204197. This article has 3 citations and is from a peer-reviewed journal.

  4. (govender2023palmoplantarkeratodermapseudoainhum pages 1-2): Kellicia Courtney Govender and Somasundram Pillay. Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an african patient: a case report. SAGE Open Medical Case Reports, Jan 2023. URL: https://doi.org/10.1177/2050313x231204197, doi:10.1177/2050313x231204197. This article has 3 citations and is from a peer-reviewed journal.

  5. (jemmott2007anunusualcause pages 2-4): Timothy Jemmott, Alethea V Foster, and Michael E Edmonds. An unusual cause of ulceration: ainhum (dactylolysis spontanea). International Wound Journal, 4:251-254, Sep 2007. URL: https://doi.org/10.1111/j.1742-481x.2007.00297.x, doi:10.1111/j.1742-481x.2007.00297.x. This article has 22 citations and is from a peer-reviewed journal.

  6. (jemmott2007anunusualcause pages 4-4): Timothy Jemmott, Alethea V Foster, and Michael E Edmonds. An unusual cause of ulceration: ainhum (dactylolysis spontanea). International Wound Journal, 4:251-254, Sep 2007. URL: https://doi.org/10.1111/j.1742-481x.2007.00297.x, doi:10.1111/j.1742-481x.2007.00297.x. This article has 22 citations and is from a peer-reviewed journal.

  7. (tchouakam2019ainhumarare pages 1-3): Diego Nitcheu Tchouakam, Joel Noutakdie Tochie, Marc Leroy Guifo, and Simeon Pierre Choukem. Ainhum, a rare mutilating dermatological disease in a female cameroonian: a case report. BMC Dermatology, Aug 2019. URL: https://doi.org/10.1186/s12895-019-0092-6, doi:10.1186/s12895-019-0092-6. This article has 16 citations and is from a peer-reviewed journal.