Lepromatous leprosy masquerading as acute sarcoidosis: a case report and literature review.

Leprosy is uncommon in North America. Because it has a prolonged incubation period and can masquerade with a variety of manifestations, many patients with leprosy experience a significant delay in diagnosis and treatment. Lepra reactions are of 2 types: reversal (type 1) and erythema nodosum leprosum (ENL) (type 2). Type 1 or reversal reactions represent an increase in cell-mediated immunity, whereas type 2 or ENL is caused by antigen-antibody complex formation and deposition after antigen release from dying lepra bacilli. This article describes the diagnostic challenges presented by a Minnesota patient eventually found to have lepromatous leprosy. That challenge was compounded by the fact that the clinical scenario closely mimicked connective tissue/immune complex disease and by the fact that the patient presented in a location where the incidence and prevalence of leprosy is extremely low.