Extensive intraglomerular thrombi of monoclonal IgM-kappa in a patient with malignant lymphoma

We describe an 80-year-old man who developed malignant lymphoma (ML) compli cated by extensive intraglomerular thrombi of immunoglobulin M (IgM)-kappa monoclonal immunoglobulin. The clinical picture was characterized by nephro tic syndrome and systemic lymphadenopathy. Laboratory examination showed mi ld anemia and a small amount of monoclonal IgM-kappa in the blood. The hist opathologic findings and surface immunoglobulin analysis of the lymph node biopsy specimen were consistent with CD5-positive diffuse large B-cell (typ e, IgM-kappa) lymphoma. The subsequent renal biopsy showed a massive deposi tion of amorphous material in the glomerular capillary lumens, subendotheli al areas, and mesangium. Nodular glomerulosclerosis was not found. An immun ofluorescent study showed that the deposits consisted of IgM-kappa monoclon al immunoglobulin. Ultrastructurally, the deposits were composed of granula r electron-dense material. Chemotherapy was effective for both the ML and n ephrotic syndrome, and the patient's urine analysis results returned to nor mal. The histopathologic manifestations of this case are rare, and the path ogenesis of these glomerular lesions was obviously associated with ML. (C) 2000 by the National Kidney Foundation, Inc.