Diffuse B cell lymphoma without lymphadenopathy accompanied by reactive histiocytosis simulating malignant histiocytosis: A report of three autopsy cases.

The clinical and autopsy findings of three cases of B cell lymphoma simulating malignant histiocytosis are reported. Case 1 was 60y.o. female, case 2 was 75y.o. male and case 3 was 61y.o. female. The presenting symptoms were pyrexia in three cases, dyspnea in case 1 and jaundice in case 2. There was no peripheral lymphadenopathy in these cases. A hyperplasia of monocytes and hemophagocytic histiocytes was seen in their bone marrow and many abnormal lymphoid cells were seen in the marrow of case 3. The lung biopsy revealed infiltration of abnormal cells in case 1. Case 1 and 2 were diagnosed as malignant histiocytosis and case 3 was diagnosed as malignant lymphoma with reactive histiocytosis. After chemotherapy using adriamycin or THP-adriamycin case 1 and 3 improved, however case 2 did not respond. The overall survivals of three cases were 26 months in case 1, 3.5 months in case 2 and 12 months in case 3.The postmortem examination showed that abnormal cells infiltrated diffusely into many organs such as lungs, liver, spleen and kidneys. Neither lymphadenopathy nor tumor-formation was seen. Infiltrating abnormal cells were positive for pan B cell antibody (L26) but negative for pan T cell antibody, lysozyme and S-100 protein.These cases indicate that a part of B cell lymphoma is accompanied by reactive histiocytosis simulating malignant histiocytosis.