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For further information, see CMDT Part 33-37: Leprosy (Hansen Disease)

Key Features

Essentials of Diagnosis

  • Pale, anesthetic macular—or nodular and erythematous—skin lesions

  • Superficial nerve thickening with resultant anesthesia

  • History of residence in endemic area in childhood

  • Acid-fast bacilli in skin lesions or nasal scrapings, or characteristic histologic nerve changes

General Considerations

  • A chronic infectious disease caused by the acid-fast rod Mycobacterium leprae

  • The mode of transmission probably is respiratory droplets and involves prolonged exposure in childhood

  • The disease is divided into two distinct types: lepromatous and tuberculoid

  • The lepromatous type occurs in persons with defective cellular immunity

  • In the tuberculoid type, cellular immunity is intact and the course is more benign


  • The disease is endemic in tropical and subtropical Asia, Africa, Central and South America, and the Pacific regions

Clinical Findings

Symptoms and Signs

  • The onset is insidious

  • The lesions involve the cooler body tissues: skin, superficial nerves, nose, pharynx, larynx, eyes, and testicles

  • Skin lesions may occur as

    • Pale, anesthetic macular lesions 1–10 cm in diameter

    • Discrete erythematous, infiltrated nodules 1–5 cm in diameter

    • Diffuse skin infiltration

  • Neurologic disturbances are caused by nerve infiltration and thickening, with resultant anesthesia, and motor abnormalities

  • Bilateral ulnar neuropathy is highly suggestive


  • The course is progressive with nodular skin lesions and slow, symmetric nerve involvement


  • The course is more benign and less progressive, with macular skin lesions and severe asymmetric nerve involvement of sudden onset

  • Intermediate ("borderline") cases are frequent. Eye involvement (keratitis and iridocyclitis), nasal ulcers, epistaxis, anemia, and lymphadenopathy may occur

Differential Diagnosis

  • Systemic lupus erythematosus

  • Sarcoidosis

  • Syphilis

  • Erythema nodosum

  • Erythema multiforme

  • Cutaneous tuberculosis

  • Vitiligo


Laboratory Tests

  • M leprae does not grow in artificial media but does grow in the footpads of armadillos

  • The lepromatous type: abundant acid-fast bacilli in the skin lesions and a negative lepromin skin test

  • The tuberculoid type: few bacilli present in the lesions and a positive lepromin skin test

Diagnostic Procedures

  • Laboratory confirmation requires the demonstration of acid-fast bacilli in a skin biopsy

  • Biopsy of skin or of a thickened involved nerve also gives a typical histologic picture



  • Combination therapy is recommended for treatment of all types of leprosy

  • For borderline and lepromatous cases (ie, multibacillary disease), the World Health Organization recommends

    • A triple oral drug regimen of rifampin, 600 mg once a month; dapsone, 100 mg/day; and clofazimine, 300 mg once a month and ...

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