Cast nephropathy and light-chain deposition disease in Waldenström macroglobulinemia.

Waldenström macroglobulinemia is a rare low-grade hematologic malignancy due to clonal proliferation of B lymphocytes responsible for immunoglobulin M (IgM) monoclonal gammopathy secreted in serum. This disease is characterized by lymphoplasmacytic tumoral infiltration of bone marrow and various organs, especially the liver and spleen. Kidney involvement in Waldenström macroglobulinemia has been described previously with reports of various forms of glomerular injury: large intracapillary IgM pseudothrombi, cryoglobulinemia-associated membranoproliferative glomerulonephritis, or amyloidosis. Interstitial infiltration by tumoral B lymphocytes is another classic pattern. Conversely, tubular involvement in the form of myeloma-like casts or basement membrane deposition of monoclonal light chain (light-chain deposition disease) is unusual. We report the occurrence of cast nephropathy associated with light-chain deposition disease in 2 patients with Waldenström macroglobulinemia, which resulted in severe and prolonged kidney failure.