Nephrotic syndrome associated with generalized amyloidosis and IgM-monoclonal proteinemia

A 67-year-old woman was admitted for nephrotic syndrome. In spite of the lack of lymphadenopathy, hepatosplenomegaly and serum hyperviscosity, remarkable monoclonal IgM-proteinemia was demonstrated. Amyloid kidney was shown by renal biopsy. However, in the bone marrow and other organs, neither proliferation nor invasion of monoclonal immunoglobulin-producing cells was revealed by immunohistological investigations of the specimens biopsied or examined at autopsy, excluding Waldenström's macroglobulinemia. Immunosuppressive chemotherapy with cyclophosphamide, vincristine and prednisolone was effective in reducing serum IgM, but could not slow the progression of renal failure. This case suggested the association of generalized amyloidosis with excessive IgM-proteinemia caused by a non-malignant mechanism.