Histiocytic lymphoma of B cell origin.

A histiocytic lymphoma with a terminal leukemic phase occurred in a 50-year-old man. Immunologic studies indicated that neoplastic cells from the peripheral blood sample, bone marrow aspirate, and lymph node carried surface immunoglobulin. Cytochemical and immunohistochemical analysis of this histiocytic lymphoma and its subsequent leukemic phase displayed a profile consistent with a lymphocytic rather than a histiocytic origin of the neoplastic cell.