lymphoplasmacytic lymphoma/Waldenstrm macroglobulinemia is characterized by the presence of a diffuse proliferation of small mature B lymphocytes, plasmacytoid lymphocytes, and plasma cells; the cells show surface Ig (usually IgM), B-cell-associated antigens, and are CD23 and CD10 negative. The t(9;14) chromosomal translocation has been found in 50% of all lymphoplasmacytic lymphoma cases. Clinical course is usually indolent, but may be associated with hyperviscosity syndrome due to excess IgM in the blood.Waldenström macroglobulinemia. SYN: immunocytoma.