Skin-nontumor / Clinical dermatology
Infectious disorders
Mycobacteria - atypical

Author: Mowafak Hamodat, MB.CH.B, MSc., FRCPC (see Authors page)

Revised:31 May 2016, last major update March 2015

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Mycobacteria [title] skin

Cite this page: Mycobacteria - atypical. website. Accessed October 23rd, 2016.
Definition / General
  • Skin disorders (ulcerations, abscesses, rheumatoid-like nodules, histiocytic reactions, panniculitis), most commonly due to M. kansasii, M. marinum, M. ulcerans
  • Non tuberculous mycobacteria are non pathogenetic; they inhabit vegetation and water (stagnant, fresh or salty) and are saprophytic in soil, on animals and within animal feces
  • Mycobacterium marinum is contracted most often in swimming pools (swimming pool granuloma, fish tank granuloma)
  • Mycobacterium ulcerans is third most common mycobacterial disease in immunocompetent after tuberculosis and leprosy; often in tropical wetlands of Central and West Africa (Buruli ulcer), particularly areas with high prevalence of schistosomiasis (Trop Med Int Health 2001;6:554)
Clinical Features
  • Upper limbs are common site of infection
  • Typically cause painless inflammatory nodules or plaques that may ulcerate and discharge
  • Mycobacterium kansasii mainly affects lung and lymph nodes, rarely causes skin lesions; has nodules which may be verrucous or become crusted ulcers; also papulopustules, cellulitis or spreading infection resembling sporotrichosis
  • Rarely, squamous cell carcinoma may arise in a chronic Buruli ulcer
Case Reports
Clinical Images

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Swimming pool granuloma

Swollen, red papules and nodules

Ulcer on the lateral surface of the fifth toe

Micro Description
  • Usually early cutaneous necrosis with abscess formation; abscess is gradually replaced by granulomatous inflammation and fibrosis
Micro Images

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Subcutis, courtesy of Dr. Mark R. Wick

Fite stain, courtesy of Dr. Mark R. Wick

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Granulomatous inflammation, A Fite stain

Molecular / Cytogenetics Description
  • PCR with liquid media facilitates species identification