Waldenstrom macroglobulinemia caused by extranodal marginal zone B-cell lymphoma - A report of six cases

Waldenstrom macroglobulinemia (WM) and its associated hyperviscosity syndro me (HVS) are generally caused by lymphoplasmacytoid lymphoma or other small B-cell lymphoproliferative disorders. WM associated with extranodal margin al zone B-cell-mucosa-associated lymphoid tissue lymphoma (EMZL/MALT-type) has not been emphasized. We describe 4 men and 2 women (age, 40-79 years) w ith clinical and laboratory manifestations of WM and EMZL/MALT-type involvi ng one or more sites: lung, pericardium/pleura, ocular adnexa, nasopharynx, minor salivary gland, glossopharyngeal fold, skin, and stomach. The follow ing immunophenotypic patterns were observed: CD20+, 6; CD43+, 3; kappa ligh t chain restriction, 5; and lambda light chain restriction, 1. All were neg ative for CD5, CD10, and cyclin D1 expression. A clonal paraproteinemia was present in each (IgM kappa, 4; IgM lambda, 1; biclonal IgM kappa/IgA kappa , 1). All 4 patients tested had elevated plasma viscosity; clinical HVS occ urred in 3, arid 2 required emergency plasmapheresis. These findings sugges t that EMZL/MALT-type can cause WM and that the laboratory evaluation of EM ZL/MALT-type should include serum protein electrophoresis/immunofixation, a nd plasma viscosity measurements and urine immunofixation in select cases. EMZL/MALT-type should be considered in the differential diagnosis in patien ts with clinicopathologic features of WM.