Malignant histiocytosis: a chronic variant.

An 18-year-old woman had unusual clinical manifestations of malignant histiocytosis (MH) including a long duration of massive splenomegaly, absence of lymphadenopathy, and a number of exacerbations characterized by sudden onset of fever. During life, a definite diagnosis could not be established. The antemortem pathology of the marrow and liver was nonspecific and non-diagnostic. The diagnosis of MH was made after postmortem examination by histologic and immunohistochemical studies. The long duration of massive splenomegaly suggests that this patient could represent a chronic form of MH.