An Autopsy Case of Malignant Histocytosis with Reed‐Sternberg‐like Cells

We report an autopsy case of malignant histiocytosis. The clinical course was rapidly progressive and terminated with jaundice and respiratory failure. Histologically, there was diffuse infiltration of large atypical cells in the liver, spleen, lymph nodes and bone marrow. It was of interest that these tumor cells contained a number of bizarre multinucleated cells histologically indistinguishable from Reed Sternberg cells of Hodgkin's disease, and that these atypical cells expressed DAKO Ml (identical to Leu Ml) and Ki‐1 antigens and also showed binding to peanut agglutinin (PNA), representative markers of Reed Sternberg cell. An absence of epithelial membrane antigen and presence of Leu Ml antigen in the tumor cells made a diagnosis of Ki‐1 lymphoma unlikely. This case study showed that giant or pleomorphic cells indistinguishable histologically and phenotypically from Reed Sternberg cells occur in malignant histiocytosis.