Clinical and pathologic features of Waldenström's macroglobulinemia in seven patients with serum monoclonal IgG or IgA.

The clinical, hematologic and pathologic findings in seven patients were similar to those of Waldenström's macroglobulinemia, but unexpectedly the serum monoclonal immunoglobulin belonged to the IgG class in five patients and to the IgA class in two. The bone marrow and lymph node lymphoid proliferation was pleomorphic, with the simultaneous presence of small lymphocytes, normal mature plasma cells and transitional lymphoplasmacytic cells. Immunofluorescence studies showed that a monoclonal immunoglobulin similar to that found in the serum was detectable on the membrane or in the cytoplasm of all the proliferating cells, which thus belonged to the same B cell clone. The study of these patients is in accordance with the concept that lymphoid disorders featured by a pleomorphic monoclonal B cell proliferation constitute a distinct clinicopathologic entity, which is not restricted to IgM-producing clones.