Multiple myeloma-associated cast nephropathy with crystal structure: case report and review of the literature.

The causes of renal failure are diverse. Among them, monoclonal gammopathy is one important but easily-missed cause in aged people. Monoclonal gammopathy may produce a large number of abnormal immunoglobulins and/or fragments and produce different kinds of deposition in tissues, including cast, crystal, fibril and granules. Cast nephropathy is considered the hallmark of the renal disease in patients with multiple myeloma. Crystaglobulinemia syndrome and crystal nephropathy, on the other hand, have been rarely reported. Herein, we report a case of multiple myeloma presented with irreversible renal failure. The biopsy showed massive crystal deposition in bone marrow and kidneys.