[Chemotherapy-induced erythema nodosum leprosum: successful treatment with thalidomide].

The severity and outcome of a chronic granulomatous infection caused by M. leprae depend on the cell-mediated immunity towards the pathogen. The disease classification is based on the host's response to M. leprae ranging from high to low resistance (polar tuberculoid leprosy to polar lepromatous leprosy). The host's position in the spectrum is not stable; leprosy reactions reflecting changed immune status may occur spontaneously or during chemotherapy. The type II reaction or erythema nodosum leprosum can most often be seen in patients with lepromatous leprosy, a multiorgan disease characterized by an unrestricted bacillary replication. Clinically, this reaction is characterized by crops of painful bright pink, dermal and subcutaneous nodules arising in clinically normal skin, in association with fever, malaise, glomerulonephritis and arthralgias. Therefore, prompt institution of immunosuppressive therapy with corticosteroids or thalidomide is recommended. This case report describes the development of erythema nodosum leprosum during chemotherapy treated successfully with thalidomide. Furthermore, immunologic effects and potential side effects of this drug are discussed.