Histiocytic lymphoma and malignant angioendotheliomatosis. One disease or two?

The case history of a patient with diffuse histiocytic lymphoma and skin lesions characteristic of malignant angioendotheliomatosis is reported. The patient initially responded to aggressive chemotherapy but quickly had a relapse, CNS disease developed, and the patient died one year after diagnosis. Microscopic, ultrastructural, and surface membrane studies showed that the intravascular tumor cells were not of endothelial origin. The morphologic similarity of the malignant intravascular cells and peripheral blood cells, as well as the demonstration of surface membrane immunoglobulin on malignant blood cells suggested that, in some cases, unusual features of malignant lymphoma may be confused with malignant angioendotheliomatosis.