Ainhum

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
    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
    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
    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
    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
    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
    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
    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
    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
    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
    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
    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
    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
    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
    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
    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: []