Light chain plasmacytoid lymphocytic lymphoma.

Introduction Waldenstrom's primary macroglobulinaemia (Waldenstrom, 1944) is characterized by serum IgM paraproteinaemia and pleomorphic infiltration consisting of lymphocytes, abnormal plasma cells and intermediate cell forms in the bone marrow and other tissues (McCallister et al., 1967; MacKenzie and Fudenberg, 1972). This pathological picture has been termed 'plasmacytoid lymphocytic lymphoma' by Lukes and Collins (1975) in their classification system for non-Hodgkin's malignant lymphomas. However, an identical tumour cell morphology has been observed in some patients in whom the IgM serum paraprotein is absent (Child et al., 1977; Tursz et al., 1977; Levine et al., 1980). The patient now described presented with the cytohistological features of 'plasmacytoid lymphocytic lymphoma' but with a paraprotein belonging to the X-light chain. Immunoperoxidase and electronmicroscopic studies are included in this report.