Disseminated Langerhans cell histiocytosis: a case report with a light microscopic and ultrastructural study.

A case of disseminated Langerhans cell histiocytosis (L.C.H.) in a 9 month-old boy is reported. The clinical picture was characterized by severe multivisceral involvement with cutaneous and bone lesions. Histological examination of the skin biopsy revealed diffuse infiltration of large mononucleated histiocytes admixed with a small number of inflammatory cells. Ultrastructural examination confirmed the Langerhans cell (L.C.) phenotype by showing intracytoplasmic Birbeck granules in the proliferating histiocytes. We report the histological and ultrastructural characteristics of our case and review the diagnostic features of L.C.H. in the light of the criteria established by the Writing Group of the Histiocytic Society in 1987.