Fatal Lucio's phenomenon in 2 patients with previously undiagnosed leprosy.

We report 2 cases of Lucio's phenomenon, a rare, aggressive, occasionally fatal type 2 reaction occurring in the diffuse nonnodular type of lepromatous leprosy. The clinical diagnosis of Lucio's phenomenon is difficult, and there are no known predictive or prognostic factors. Despite institution of aggressive treatment after diagnosis, our 2 cases had fatal outcomes.