By Gary M. White, MD
Leprosy is a chronic infection by Mycobacterium leprae, which has a preference for the skin and peripheral nerves.
According to the CDC, 178 cases of leprosy were reported in the US in 2015. Cases from Hawaii, Texas, California, Louisiana, New York and Florida made up 72% of cases. Contact with the armadillo is a risk factor for development of leprosy and cases have been reported in the US in Texas and Florida.
The typical lesion in the tuberculoid type is a large annular erythematous plaque with an involuting, hypopigmented, anesthetic center. Nerve enlargement (e.g. greater auricular, superficial peroneal) with muscle atrophy may occur. In lepromatous leprosy, nodular infiltration of the face and ears and elsewhere is characteristic. The eyebrows may be progressively lost. Alopecia may occur in the scalp as well [Int J Trichol 2015;7:74-6].
The histoid type of LL presents as multiple skin-colored soft to firm papulonodules, subcutaneous nodules, or fixed plaques. Lesions resembling neurofibromatosis and molluscoid lesions of histoid leprosy are also known. The underlying skin is usually normal.
Tremendous mutilating deformities of the hands and feet may occur in chronic disease. Without the ability to feel pain, injuries occur to digits from simple everyday activities. Trauma, ulcerations and infections lead to scarring and loss of tissue. Fingers and toes become shortened and deformed.
Slit smear for diagnosis may be performed on, for example, the earlobes. Application of a suitable topical local anesthetic before the procedure can decrease the pain. All family members should be evaluated for hypopigmented and anesthetic macules.
The latest recommended treatment guidelines for multi-drug therapy should be consulted. In the past, the following have been recommended.
For paucibacillary disease: rifampicin (600 mg monthly, supervised) plus dapsone (100 mg/day), both for 6 months.
For multibacillary disease: rifampicin (600 mg) and clofazimine (300 mg) monthly, supervised, plus dapsone (100 mg/day) and clofazimine (50 mg/day) for 2 years preferably to smear negativity.
Infiltrated plaques on the back of a man who frequently visited Mexico.
Lepromatous Leprosy, Histiocytoid type. Courtesy James Steger, MD
Infiltrated plaques of the face. Courtesy Steven H Goldberg, MD
Borderline Tuberculoid Leprosy. Courtesy James Steger, MD