Review Question - QID 106735

This patient has a classic skin lesion with numbness and a palpably enlarged peripheral nerve suggestive of leprosy. Leprosy is caused by Mycobacterium leprae infection.

Hansen's disease is a chronic granulomatous disease caused by infection with the bacterial organism Mycobacterium leprae. The primary areas affected are the skin and peripheral nerves. Two clinical findings that are important in the diagnosis of leprosy are the characteristic cutaneous lesion and areas of anesthesia. Patients may often have cuts or burns to the affected area, which they do not recall suffering because the affected area has lost nociception.

Hsu et al. review the presentation of leprosy. Leprosy can present broadly in two ways: first, as tuberculoid leprosy, or second, as lepromatous leprosy. Tuberculoid leprosy is less severe and usually presents with a single well-demarcated and hypopigmented skin lesion. The edges of the lesion often appear thickened, and peripheral nerves, especially the ulnar nerve, may be palpably enlarged. The lepromatous form of the disease is more generalized, and can present with the classic “Leonine facies” (see Illustration A).

Legendre et al. review the diagnosis and treatment of leprosy. Diagnosis is based on the clinical findings discussed above in conjunction with skin biopsy or peripheral nerve biopsy demonstrating Mycobacterium (Figure B). Treatment generally consists of dapsone and rifampin, often with clofazimine. Other treatment options include moxifloxacin or clarithromycin. The tuberculoid form may be treated for up to 6 months, while the lepromatous form may need to be treated for 5 years.

Figure A is a clinical image depicting tuberculoid leprosy on the hand of a patient. Figure B is a biopsy image showing a granulomatous response to mycobacterial organisms in lepromatous leprosy. Illustration A depicts the Leonine facies seen in lepromatous leprosy. Illustration B is a WHO world map showing the prevalence of leprosy.

Incorrect Answers:
Answer 1: Sarcoidosis can cause hypopigmented skin lesions, but the clinical findings of anesthesia and biopsy findings are consistent with leprosy.
Answer 3: Sporothrix schenckii causes sporotrichosis, which causes an ascending lymphangitis classically seen in rose gardeners.
Answer 4: Contact dermatitis is a type 4 hypersensitivity reaction following contact with certain compounds,(e.g., poison ivy, nickel, etc).
Answer 5: Poxviruses can cause molluscum contagiosum, which presents with a single dome-shaped lesion with central umbilication.