Ainhum

Complex MONDO:0007074 Dermatologic Disease Musculoskeletal Disease

Ainhum (dactylolysis spontanea) is a rare disorder characterized by progressive constricting bands of the digits, most often the fifth toe, leading to distal swelling, pain, and eventual autoamputation.

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Mappings
0
Definitions
0
Inheritance
4
Pathophysiology
0
Histopathology
4
Phenotypes
0
Pathograph
0
Genes
1
Treatments
0
Subtypes
4
Differentials
0
Datasets
0
Trials
0
Models
2
Literature
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References

2
DOI:10.1177/2050313x231204197
Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an African patient: A case report
No top-level findings curated for this source.
DOI:10.1186/s12895-019-0092-6
Ainhum, a rare mutilating dermatological disease in a female Cameroonian: a case report
No top-level findings curated for this source.
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Pathophysiology

4
Constricting groove forms around proximal toe
A groove or fissure of constricting tissue develops around a toe, most often the fifth toe.
pedal digit 5 link
Show evidence (3 references)
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"a groove or fissure of constricting tissue forms around the proximal end of the fifth toe."
The abstract describes the initiating constriction groove around the fifth toe.
PMID:12500788 SUPPORT Human Clinical
"Dactylolysis spontanea is an idiopathic condition affecting the fifth toe, and sometimes other toes"
Radiological survey notes fifth toe predominance with possible involvement of other toes.
PMID:1539609 SUPPORT Human Clinical
"It usually affects the fifth toe bilaterally"
Case report emphasizes typical bilateral fifth toe involvement.
Progressive constriction encircles the toe
The constriction groove progresses to encircle the toe.
Show evidence (1 reference)
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"Eventually, the groove extends to encircle the toe, the underlying structures are absorbed and the toe autoamputates."
The abstract notes progression from groove to encircling constriction.
Absorption of underlying structures
Progressive constriction leads to absorption of underlying tissues and bone.
Show evidence (1 reference)
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"the underlying structures are absorbed and the toe autoamputates."
The abstract explicitly links constriction to absorption of underlying structures.
Toe autoamputation
End-stage constriction results in spontaneous autoamputation of the toe.
Show evidence (1 reference)
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"the toe autoamputates."
The abstract describes autoamputation as the end-stage outcome.
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Phenotypes

4
Integument 1
Skin ulcer Skin ulcer (HP:0200042)
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."
Case report notes foot ulceration as a presentation.
Limbs 1
Autoamputation of digits Autoamputation of digits (HP:0007460)
Show evidence (3 references)
PMID:1539609 SUPPORT Human Clinical
"Ainhum is the spontaneous autoamputation of toes as a result of the formation of a constricting band."
Case report defines ainhum by spontaneous autoamputation due to constricting band formation.
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"He reported that his left fifth toe had autoamputated some months before."
Case report documents autoamputation of a digit.
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"the underlying structures are absorbed and the toe autoamputates."
Abstract describes autoamputation as the outcome of progressive constriction.
Musculoskeletal 1
Osteolysis Osteolysis (HP:0002797)
Show evidence (1 reference)
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"Radiograph of the right fifth toe showed absorption of the proximal and intermediate phalanges"
Radiograph showed bone absorption, consistent with osteolysis.
Prenatal and Birth 1
Digital constriction ring Digital constriction ring (HP:0010491)
Show evidence (1 reference)
DOI:10.1111/j.1742-481x.2007.00297.x SUPPORT Human Clinical
"a groove or fissure of constricting tissue forms around the proximal end of the fifth toe."
Constricting tissue groove corresponds to a digital constriction ring.
💊

Treatments

1
Surgical excision of constriction band with disarticulation
Action: surgical procedure MAXO:0000004
Surgical management includes excision of the constricting band with disarticulation at the metatarsophalangeal joint and skin closure.
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."
Case report documents surgical excision and disarticulation as treatment.
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Differential Diagnoses

4

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

Pseudo-ainhum
Overlapping Features Pseudo-ainhum presents with annular constriction of digits secondary to identifiable hereditary or nonhereditary conditions.
Distinguishing Features
  • Secondary to an identifiable precipitating factor or underlying disease rather than idiopathic.
Show evidence (3 references)
PMID:27190888 SUPPORT Human Clinical
"It is to be differentiated from Pseudo-ainhum that occurs secondary to some hereditary and nonhereditary diseases that lead to annular constriction of digits."
Case report explicitly contrasts true ainhum with pseudo-ainhum due to secondary causes.
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."
Case report notes pseudo-ainhum has precipitating factors and should be differentiated.
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."
Review case report describes pseudo-ainhum as secondary to hereditary or nonhereditary diseases.
Vohwinkel syndrome MONDO:0007422
Overlapping Features Hereditary keratoderma with ainhumoid constriction bands that can mimic true ainhum.
Show evidence (1 reference)
PMID:25624138 SUPPORT Human Clinical
"ainhumoid palmoplantar keratoderma, which is of genetic origin and occurs for instance in Vohwinkel syndrome."
Case series notes ainhumoid keratoderma occurs in Vohwinkel syndrome, supporting it as a differential.
Olmsted syndrome Not Yet Curated MONDO:0031421
Overlapping Features Mutilating palmoplantar keratoderma with ainhum and digital autoamputation.
Show evidence (1 reference)
PMID:17344790 SUPPORT Human Clinical
"Olmsted syndrome is a rare disorder characterized by symmetrical sharply marginated mutilating keratoderma of palms & soles & hyperkeratotic plaques around the body orifices, onychodystrophy, ainhum & amputation of digital phalanges"
Olmsted syndrome includes ainhum and digital amputation, warranting differential consideration.
Critical limb ischemia Not Yet Curated MONDO:0000491
Overlapping Features Critical limb ischemia can cause spontaneous sub-amputation and may mimic advanced ainhum.
Show evidence (1 reference)
PMID:41017837 SUPPORT Human Clinical
"Spontaneous sub-amputation is a rare manifestation of critical limb ischemia (CLI)"
Case report documents spontaneous sub-amputation due to critical limb ischemia, a clinical mimic.
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Literature Summaries

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.

{ }

Source YAML

click to show 
name: Ainhum
creation_date: '2026-02-04T17:27:57Z'
updated_date: '2026-02-17T21:53:14Z'
category: Complex
description: >-
  Ainhum (dactylolysis spontanea) is a rare disorder characterized by
  progressive constricting bands of the digits, most often the fifth toe,
  leading to distal swelling, pain, and eventual autoamputation.
synonyms:
- Dactylolysis spontanea
- Ainhum (dactylolysis spontanea)
disease_term:
  preferred_term: ainhum
  term:
    id: MONDO:0007074
    label: ainhum
parents:
- Dermatologic Disease
- Musculoskeletal Disease
pathophysiology:
- name: Constricting groove forms around proximal toe
  description: A groove or fissure of constricting tissue develops around a toe,
    most often the fifth toe.
  locations:
  - preferred_term: pedal digit 5
    term:
      id: UBERON:0003635
      label: pedal digit 5
  evidence:
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    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 abstract describes the initiating constriction groove
      around the fifth toe.
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dactylolysis spontanea is an idiopathic condition affecting the fifth
      toe, and sometimes other toes"
    explanation: Radiological survey notes fifth toe predominance with possible
      involvement of other toes.
  - reference: PMID:1539609
    reference_title: "Case report: ainhum (spontaneous dactylolysis) in a 65-year-old American black man."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It usually affects the fifth toe bilaterally"
    explanation: Case report emphasizes typical bilateral fifth toe involvement.
- name: Progressive constriction encircles the toe
  description: The constriction groove progresses to encircle the toe.
  evidence:
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    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 abstract notes progression from groove to encircling
      constriction.
- name: Absorption of underlying structures
  description: Progressive constriction leads to absorption of underlying
    tissues and bone.
  evidence:
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the underlying structures are absorbed and the toe autoamputates."
    explanation: The abstract explicitly links constriction to absorption of
      underlying structures.
- name: Toe autoamputation
  description: End-stage constriction results in spontaneous autoamputation of
    the toe.
  evidence:
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the toe autoamputates."
    explanation: The abstract describes autoamputation as the end-stage outcome.
phenotypes:
- name: Digital constriction ring
  category: Dermatologic
  description: Constricting ring encircles the affected digit.
  phenotype_term:
    preferred_term: Digital constriction ring
    term:
      id: HP:0010491
      label: Digital constriction ring
  evidence:
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a groove or fissure of constricting tissue forms around the proximal
      end of the fifth toe."
    explanation: Constricting tissue groove corresponds to a digital
      constriction ring.
- name: Osteolysis
  category: Musculoskeletal
  description: Resorption of phalanges is seen in affected digits.
  phenotype_term:
    preferred_term: Osteolysis
    term:
      id: HP:0002797
      label: Osteolysis
  evidence:
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Radiograph of the right fifth toe showed absorption of the proximal
      and intermediate phalanges"
    explanation: Radiograph showed bone absorption, consistent with osteolysis.
- name: Autoamputation of digits
  category: Musculoskeletal
  description: Progressive constriction leads to autoamputation of the affected
    digit.
  phenotype_term:
    preferred_term: Autoamputation of digits
    term:
      id: HP:0007460
      label: Autoamputation of digits
    located_in:
      preferred_term: toe
      term:
        id: UBERON:0001466
        label: pedal digit
  evidence:
  - reference: PMID:1539609
    reference_title: "Case report: ainhum (spontaneous dactylolysis) in a 65-year-old American black man."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ainhum is the spontaneous autoamputation of toes as a result of the
      formation of a constricting band."
    explanation: Case report defines ainhum by spontaneous autoamputation due to
      constricting band formation.
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "He reported that his left fifth toe had autoamputated some months before."
    explanation: Case report documents autoamputation of a digit.
  - reference: DOI:10.1111/j.1742-481x.2007.00297.x
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the underlying structures are absorbed and the toe autoamputates."
    explanation: Abstract describes autoamputation as the outcome of progressive
      constriction.
- name: Skin ulcer
  category: Dermatologic
  description: Ainhum can present with 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: Case report notes foot ulceration as a presentation.
progression:
- phase: Stage progression
  notes: Radiological staging identifies lesions in different stages, supporting
    stepwise progression.
  evidence:
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "frequently bilateral, with lesions in different stages."
    explanation: Radiological survey reports lesions in different stages within
      patients.
diagnosis:
- name: Radiographic examination of the feet
  description: Radiography aids early diagnosis and staging.
  diagnosis_term:
    preferred_term: radiograph imaging procedure
    term:
      id: MAXO:0000595
      label: radiograph imaging procedure
  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: Radiological examination is described as facilitating diagnosis
      and staging.
prevalence:
- population: Radiographic survey population (Chicago, 1977-1999)
  notes: 102 cases identified among 6000 foot radiographs in a mainly African
    American population.
  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: Radiological survey population and timeframe.
  - reference: PMID:12500788
    reference_title: "Ainhum (dactylolysis spontanea): a radiological survey of 6000 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "102 patients were diagnosed with dactylolysis spontanea or ainhum."
    explanation: Survey reports number of identified ainhum cases.
biochemical: []
genetic: []
environmental: []
treatments:
- name: Surgical excision of constriction band with disarticulation
  description: Surgical management includes excision of the constricting band
    with disarticulation at the metatarsophalangeal joint and skin closure.
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: MAXO:0000004
      label: surgical procedure
    qualifiers:
    - predicate:
        preferred_term: surgical procedure
        term:
          id: NCIT:C15329
          label: Surgical Procedure
      value:
        preferred_term: excision
        term:
          id: NCIT:C15232
          label: Excision
  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: Case report documents surgical excision and disarticulation as
      treatment.
datasets: []
differential_diagnoses:
- name: Pseudo-ainhum
  description: Pseudo-ainhum presents with annular constriction of digits
    secondary to identifiable hereditary or nonhereditary conditions.
  distinguishing_features:
  - Secondary to an identifiable precipitating factor or underlying disease
    rather than idiopathic.
  evidence:
  - reference: PMID:27190888
    reference_title: "Ainhum - A Rare Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is to be differentiated from Pseudo-ainhum that occurs secondary
      to some hereditary and nonhereditary diseases that lead to annular constriction
      of digits."
    explanation: Case report explicitly contrasts true ainhum with pseudo-ainhum
      due to secondary causes.
  - 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: Case report notes pseudo-ainhum has precipitating factors and
      should be differentiated.
  - 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: Review case report describes pseudo-ainhum as secondary to
      hereditary or nonhereditary diseases.
- name: Vohwinkel syndrome
  description: Hereditary keratoderma with ainhumoid constriction bands that can
    mimic true ainhum.
  disease_term:
    preferred_term: Vohwinkel syndrome
    term:
      id: MONDO:0007422
      label: keratoderma hereditarium mutilans
  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: Case series notes ainhumoid keratoderma occurs in Vohwinkel
      syndrome, supporting it as a differential.
- name: Olmsted syndrome
  description: Mutilating palmoplantar keratoderma with ainhum and digital
    autoamputation.
  disease_term:
    preferred_term: Olmsted syndrome
    term:
      id: MONDO:0031421
      label: Olmsted syndrome
  evidence:
  - reference: PMID:17344790
    reference_title: "Olmsted syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Olmsted syndrome is a rare disorder characterized by symmetrical sharply
      marginated mutilating keratoderma of palms & soles & hyperkeratotic plaques
      around the body orifices, onychodystrophy, ainhum & amputation of digital phalanges"
    explanation: Olmsted syndrome includes ainhum and digital amputation,
      warranting differential consideration.
- name: Critical limb ischemia
  description: Critical limb ischemia can cause spontaneous sub-amputation and
    may mimic advanced ainhum.
  disease_term:
    preferred_term: limb ischemia
    term:
      id: MONDO:0000491
      label: limb ischemia
  evidence:
  - reference: PMID:41017837
    reference_title: "Spontaneous sub-amputation from atypical critical limb ischemia in a patient without classical risk factors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Spontaneous sub-amputation is a rare manifestation of critical limb
      ischemia (CLI)"
    explanation: Case report documents spontaneous sub-amputation due to
      critical limb ischemia, a clinical mimic.
references:
- reference: DOI:10.1177/2050313x231204197
  title: 'Palmoplantar keratoderma, pseudo-ainhum and knuckle pads in an African patient:
    A case report'
  findings: []
- reference: DOI:10.1186/s12895-019-0092-6
  title: 'Ainhum, a rare mutilating dermatological disease in a female Cameroonian:
    a case report'
  findings: []