Malignant lymphoma and erythrophagocytosis simulating malignant histiocytosis.

Six patients with malignant lymphoma are described, in whom a syndrome that mimicked malignant histiocytosis clinically and pathologically developed as a terminal event. The clinical course was characterized by hepatosplenomegaly, fever, and a rapid fall in all hematologic counts. Survival from onset of this syndrome was less than six weeks. Pathologically, activation of benign histiocytes with marked erythrophagocytosis was seen throughout the reticuloendothelial system. Disseminated lymphoma was also evident but was grossly and microscopically segregated from the erythrophagocytic process. Immunologic and cytochemical studies in two cases indicated the lymphomas to be of peripheral T cell origin, whereas the phagocytic cells had markers characteristic of histiocytes. A likely mechanism for this syndrome is the production of lymphokines (macrophage-activating factors) by neoplastic T lymphocytes.