Lymphoplasmacytic lymphoma. A clinicopathologic study of a previously unrecognized composite variant

Six cases are reported of a previously undescribed unusual composite variant of lymphoplasmacytic lymphoma that is not readily classifiable by either the Rappaport or the Lukes and Collins classifications, or by the recently proposed Working Formulation. These cases are characterized by a partly nodular, partly diffuse proliferation of lymphoid cells surrounded by a separate, zonally distinct proliferation of large plasmacytoid cells. The latter cells are located in medullary and paracortical areas in lymph nodes and in the marginal zone of the white pulp and in the red pulp in the spleen. This distinct zonal characteristic was noted in the small bowel as well in one case. Five of our six patients were male, and their ages ranged from 46 to 68 years. Three had a monoclonal serum IgM and one had hyperglobulinemia that was not further characterized. Three had evidence of an altered immune state. In all cases, monoclonal IgM was demonstrated in involved tissues by an immunoperoxidase technique. These cases are unusual because of the unique topographic segregation of the varying types of tumor cells in all cases, and because of the association of paraproteinemia with nodular lymphoma in three. The resemblance of this tumor to the plasma cell variant of giant lymph node hyperplasia with which two cases were originally confused, and to lymph nodes in patients with autoimmune diseases, may be responsible for its lack of recognition.