Leprosy in Adult
Alerts and Notices
Synopsis

Leprosy is classified into 5 disease types based on clinical, immunologic, and pathologic criteria:
- Tuberculoid leprosy (TT)
- Borderline tuberculoid leprosy (BT)
- Midborderline leprosy (BB)
- Borderline lepromatous leprosy (BL)
- Lepromatous leprosy (LL)
Transmission of leprosy is still not completely understood. The average incubation period for M. leprae is about 5 years, with a range from 2 to over 30 years. Leprosy in returning tourists or travelers is exceedingly rare.
Mycobacterium leprae has a predilection for the cooler parts of the body, skin, peripheral nerves, upper respiratory system, anterior eye chambers, and testes. Peripheral neuropathy may occur across the spectrum before, during, and after treatment. Small nerve fibers conveying fine touch, temperature, and pain sensations are the most impaired. During immune exacerbations (reactions), fever, arthralgias, neuritic pain, uveitis, and orchitis may occur.
Mycobacterium lepromatosis is a newly identified mycobacterium that usually causes diffuse lepromatous or lepromatous leprosy. The significance of infection with M. lepromatosis is still not clearly understood.
Codes
ICD10CM:A30.9 – Leprosy, unspecified
SNOMEDCT:
81004002 – Leprosy
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
Hypopigmented patches:Erythematous macules:
- Psoriasis
- Seborrheic dermatitis
- Tinea corporis
- Nummular dermatitis (nummular eczema)
- Syphilis
- Mycosis fungoides
- Psoriasis
- Leishmaniasis (Old World and New World)
- Seborrheic dermatitis
- Tinea corporis
- Granuloma annulare
- Nummular dermatitis (nummular eczema)
- Lichen planus
- Sarcoidosis
- Keloids
- Dermatofibromas
- Blastomycosis
- Tuberculosis
- Leishmaniasis (Old World and New World)
- Yaws
- Syphilis
- Lymphoma
- Metastases
- Erythema nodosum
Histoid leprosy clinically simulates:
- Xanthoma
- Neurofibroma
- Dermatofibromas
- Reticulohistiocytosis
- Sarcoidosis
- Keloids
- Molluscum contagiosum
- Mycobacterial spindle cell pseudotumor
- Papulonodular variant of secondary syphilis sparing the palms and soles
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Therapy
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References
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Last Reviewed:12/14/2017
Last Updated:12/14/2017
Last Updated:12/14/2017