Dermatological mycobacterium infecions

skin mycobacterial diseases

• leprosy
  • only in human
• cutaneous TB
  • only in human
• non-TB mycobacterium (NTM)
  • water-borne

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
  • multiple skin lesion
  • widespread, symmetrical
  • loss of sensation at ...
    • in histopathology diffuse infiltrate of foamy histiocytes (macrophages) in dermis
    • Leonine facies: madarosis, saddle nose

diagnosis

• WHO criteria: one or more cardinal signs

1. skin lesion consistent with leprosy with definite sensory loss
2. thickened nerve, peripheral neuropathy
3. skin smear...

treatment

• MB >5 lesions
• PB 1-5 lesions

leprosy reaction

• can develop at anytime on clinical course
  • either before or after commencement of treatment
  • even after completion of treatment
• incidence 20-60% in multiple studies

• Type 1 reversal reaction
  • cell-mediated delayed hypersensitivity
  • reddish, swollen, warm, painful, tender
  • systemic condition fair
• Type 2 erythema nodosum leprosum (ENL)
  • antigen-antibody immune complex reaction
  • multiple, distributed bilaterally and symmetrically
  • with high grade fever and malaise

treatment of leprosy reaction

• antipyretics, NSAIDs
• steroid
• immunosuppressant

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

skin NTM

all manifest in similar skin lesions, eruptions

• M. ulcerans = Buruli ulcer
• M. chelonae
• M. marinum - highest incidence
  • contact with tropical fish
• M. avium
  • long-maintained hot bath
  • hot spring
• M. peregrinum
• M. massiliense (M. abscessus subsp. massiliense)