Dermatological mycobacterium infecions

skin mycobacterial diseases

• leprosy
  • only in human
• cutaneous TB
  • only in human
• non-TB mycobacterium (NTM)
  • water-borne
  • M. ulcerans = Buruli ulcer
  • M. chelonae
  • M. marinum - highest incidence
  • M. avium - long-maintained hot bath

when to suspect

• skin symptoms without inflammatory sings (pain, swelling, redness)
• slow progression
• specific patient background
  • occupation, living place, triggering event

leprosy

• manifests in skin and peripheral nerves
• papule, macule, plaque, hypopigmentation, nodule
• loss of sensation, paralysis, amyotrophy
• incubation months to >30 years

Ridley-Jopling classification

• TT - tuberculoid
• BT - borderline tuberculoid
• BB - borderline borderline
• BL - borderline lepromatous
• LL - lepromatous

• TT direction - abnormal or significant immune response (granulomatous) against few M. leprae bacilli
  • PB in WHO classification
  • infiltrated plaque
  • well-defined, sharp border
  • single skin lesion
  • localized, asymmetrical
  • loss of sensation at skin lesion
    • in histopathology nerves are surrounded by granuloma
• LL direction - least cellular immunity or allergic reaction against much amount of M. leprae bacilli
  • MB in WHO classification
  • macule, papule, nodule

cutaneous TB

• estimated 1-2% of all TB patients
• diverse range of symptoms

route of transmission

• exogenous inoculation
  • ulcer,
  • tuberculosis verrucosa cutis, warty tuberculosis
  • orificial tuberculosis - direct contact of M.t. contained in sputum from pulmonary TB
• endogenous spread from internal TB
  • abscess,
  • scrofuloderma - emerged from lymphadenitis
• hematogenous
  • nodule, abscess, patch
  • as part of miliary tuberculosis
  • immunocompromised host, children
• tuberculid - allergic reaction against M. tuberculosis
  • erythema, papule
  • in immunocompetent patient
  • skin biopsy of the eruption shows no bacteria
  • strong positivity of Mantoux test
  • Bazin erythema
    • usually localized to lower legs

treatment

• same as of systemic tuberculosis