Histiocytic medullary reticulosis presenting as Mucha-Habermann disease.

Histiocytic medullary reticulosis (HMR) is a rare, progressive, fatal reticuleondothelial proliferative disorder. It was diagnosed in a 10-year-old boy who had pityriasis lichenoides et varioliformis acuta of Mucha-Haberman which was controlled by dapsone for 2 years. One month after cessation of dapsone therapy, cutaneous tumors associated with fever, lymphadenopathy, and hepatosplenomegaly developed. Tissue biopsy specimens of skin, liver, spleen, lymph nodes, and a bone marrow aspirate demonstrated histiocytic erythrophagocytosis and atypical histiocytosis compatible with HMR. A rapidly progressing, fatal course followed despite intensive chemotherapy.