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InfectionCommonICD-10 L08.89

Pitted keratolysis

Keratolysis plantare sulcatum · ringed keratolysis · sweaty-foot disease

Pitted keratolysis is a superficial cutaneous infection of the plantar stratum corneum caused by Kytococcus sedentarius, Corynebacterium, Dermatophilus congolensis and other Gram-positive bacteria. Profuse hyperhidrosis and occlusion provide the moist alkaline environment for bacterial protease activity, producing characteristic pitted erosions and foul foot odour. It is a very common cause of foot odour and pain mimicking plantar verruca, tinea pedis and palmoplantar punctate keratoderma.

CurrentLast reviewed 16 May 2026

Microbiology

  • Multiple Gram-positive bacteria implicated:
    • Kytococcus sedentarius (formerly Micrococcus sedentarius).
    • Corynebacterium species.
    • Dermatophilus congolensis.
    • Actinomyces keratolytica.
  • Bacterial protease + sulphur compound production → keratin degradation + foul odour.
  • Triggers: hyperhidrosis, occlusive footwear (boots, military / industrial), prolonged immersion, hot humid climates, sports.

Clinical features

  • Discrete and confluent shallow pits (1-3 mm) in the stratum corneum of weight-bearing plantar skin and toe pads.
  • Pits often coalesce into superficial erosions and erythematous patches when soaked.
  • Strong unpleasant cheese-like / sulphurous foot odour (bromhidrosis).
  • Asymptomatic in many; tenderness with walking in some; pruritus or burning in moist conditions.
  • Hyperhidrosis usually obvious.
  • Palmar variant uncommon (heavy occupation, military gloves).

Investigations

  • Clinical diagnosis.
  • Wood lamp: coral-red fluorescence (overlap with erythrasma) in some cases.
  • KOH negative for fungal hyphae (excludes tinea pedis).
  • Bacterial swab rarely needed unless atypical / resistant.

Differentials

  • Tinea pedis — interdigital scaling, KOH+; less odour.
  • Plantar verruca — discrete, punctate haemorrhages, painful, no pits.
  • Punctate palmoplantar keratoderma — hereditary; symmetric punctate keratin plugs without pitting / odour.
  • Pitting of arsenical keratoses — historical chronic arsenic exposure; risk of cSCC.
  • Basal cell naevus syndrome (Gorlin) — palmoplantar pits; family history; basal cell carcinomas.
  • Punctate porokeratosis.

Management

  • Treat hyperhidrosis:
    • 20% aluminium chloride hexahydrate (Driclor) overnight on dry feet, 2-3×/week, then weekly.
    • Glycopyrronium bromide 1-4% formulation (specialist).
    • Iontophoresis or onabotulinumtoxinA for refractory cases.
  • Topical antibacterials:
    • Clindamycin 1% or erythromycin 2% solution BD for 2-4 weeks.
    • Fusidic acid 2% cream.
    • Benzoyl peroxide 5% gel.
  • Footwear hygiene: breathable shoes, regular sock change, antimicrobial powders.
  • Avoid prolonged occlusion; dry feet thoroughly after washing.
  • Recurrence is common — long-term aluminium chloride / clindamycin solution often required.

References

  1. Singh G, Naik CL. Pitted keratolysis. Indian J Dermatol Venereol Leprol. 2005;71:213-215.
  2. Longshaw CM et al. Identification of Kytococcus sedentarius and Corynebacterium species in pitted keratolysis. Br J Dermatol. 2002;146:1058-1062.
  3. Gillum RL et al. Pitted keratolysis. Cutis. 1992;50:329-330.
  4. British Association of Dermatologists. Pitted keratolysis — patient information leaflet. London: BAD; 2022.

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