Leukemic malignant histiocytosis.

Abstract

Clinical, morphological, and ultrastructual studies are presented of three cases which had been diagnosed from lymph node biopsy as malignant histiocytosis. Three patients had a diffuse type of malignant histiocytosis and developed a leukemic phase at admission. Three patients survived for 1, 4 and 1 months after diagnosis. The neoplastic cells are characterized morphologically in the lymph nodes and in the peripheral blood by light microscopy and in two cases by electron microscopy also. These appear to be a spectrum of cell types in the leukemic malignant histiocytosis ranging from primitive reticulum cells or histiocytes to more differentiated monocytoid cells. No evidence for differentiation toward granulocytes was seen morphologically or immunohistochemically. The leukemic phase of malignant histiocytosis appears to be closely related to or identical histiocytic or monocytic leukemia (Schilling type) and should be differentiated from hairy cell leukemia. Necropsy findings from three cases are shortly reviewed.