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  • 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.


Leprosy (Hansen disease) is a chronic infectious disease caused by the acid-fast rod M leprae. The mode of transmission probably is respiratory and involves prolonged exposure in childhood. The disease is endemic in tropical and subtropical Asia, Africa, Central and South America, and the Pacific regions, and rarely seen sporadically in the southern United States.


A. 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; discrete erythematous, infiltrated nodules; or diffuse skin infiltration. Neurologic disturbances are caused by nerve infiltration and thickening, with resultant anesthesia, and motor abnormalities. Bilateral ulnar neuropathy is highly suggestive. In untreated cases, disfigurement due to the skin infiltration (eFigure 35–15) and nerve involvement may be extreme, leading to trophic ulcers, bone resorption, and loss of digits.

eFigure 35–15.

Leprosy. Leprosy, caused by Mycobacterium leprae, can cause generalized or diffuse skin involvement, and may result in skin swelling and thickening due to an inflammatory infiltrate. Other organs such as the eyes, nose, and testes may be involved. (Public Health Image Library, CDC)

The disease is divided clinically and by laboratory tests into two distinct types: lepromatous and tuberculoid. The lepromatous type (also referred to as multibacillary leprosy) occurs in patients with defective cellular immunity. The course is progressive, with nodular skin lesions; slow, symmetric nerve involvement; abundant acid-fast bacilli in the skin lesions; and a negative lepromin skin test. In the tuberculoid type (paucibacillary leprosy), cellular immunity is intact and the course is more benign and less progressive, with macular skin lesions, severe asymmetric nerve involvement of sudden onset with few bacilli present in the lesions, and a positive lepromin skin test. Intermediate ("borderline") cases are frequent. Eye involvement (keratitis and iridocyclitis), nasal ulcers, epistaxis, anemia, and lymphadenopathy may occur.

B. Laboratory Findings

Laboratory confirmation of leprosy 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. M leprae does not grow in artificial media but does grow in the foot pads of armadillos.


The skin lesions of leprosy often resemble those of SLE, sarcoidosis, syphilis, erythema nodosum, erythema multiforme, cutaneous tuberculosis, and vitiligo.


Kidney failure and hepatomegaly ...

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