Skin nontumor

Infectious disorders


Last author update: 1 March 2015
Last staff update: 12 September 2022

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PubMed Search: Mycobacteria skin

See Also: Mycobacteria non-TB

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Mycobacteria-atypical. website. Accessed September 28th, 2023.
Definition / general
  • Skin disorders (ulcerations, abscesses, rheumatoid-like nodules, histiocytic reactions, panniculitis), most commonly due to M. kansasii, M. marinum, M. ulcerans
  • Nontuberculous mycobacteria are nonpathogenetic; 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

Microscopic (histologic) description
  • Usually early cutaneous necrosis with abscess formation; abscess is gradually replaced by granulomatous inflammation and fibrosis
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.


Fite stain

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Granulomatous inflammation, a Fite stain

Molecular / cytogenetics description
  • PCR with liquid media facilitates species identification
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