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

Abstract

We describe an 80-year-old man who developed malignant lymphoma (ML) complicated by extensive intraglomerular thrombi of immunoglobulin M (IgM)-Κ monoclonal immunoglobulin. The clinical picture was characterized by nephrotic syndrome and systemic lymphadenopathy. Laboratory examination showed mild anemia and a small amount of monoclonal IgM-Κ in the blood. The histopathologic findings and surface immunoglobulin analysis of the lymph node biopsy specimen were consistent with CD5-positive diffuse large B-cell (type, IgM-Κ) lymphoma. The subsequent renal biopsy showed a massive deposition of amorphous material in the glomerular capillary lumens, subendothelial areas, and mesangium. Nodular glomerulosclerosis was not found. An immunofluorescent study showed that the deposits consisted of IgM-Κ monoclonal immunoglobulin. Ultrastructurally, the deposits were composed of granular electron-dense material. Chemotherapy was effective for both the ML and nephrotic syndrome, and the patient's urine analysis results returned to normal. The histopathologic manifestations of this case are rare, and the pathogenesis of these glomerular lesions was obviously associated with ML.