Crystalline glomerular inclusions in multiple myeloma.

Prominent crystalline inclusions were noted in the glomeruli of a 57-year-old man with a 6-month history of swelling and pain in the hands, slight proteinuria, and elevated serum creatinine and BUN. The crystalline inclusions were most prominent in the visceral epithelium but were also noted in endothelial and mesangial cells, in the parietal epithelium, and in the epithelial cells of the proximal tubules. On electron microscopy the crystalline structures were of various geometric shapes but had no definite substructure. Immunofluorescence was negative. The patient was considered to have a hitherto undescribed metabolic disease. Several months later the patient underwent an operation for carpal tunnel syndrome and amyloid deposits, crystalline inclusions similar to those noted in the kidney were observed in the synovial tissue. Shortly after this the patient was found to have multiple myeloma of IgG, kappa type with Bence Jones proteinuria. Lymphoplasmacytic cells in the bone marrow contained the same crystalline inclusions noted in the kidney and synovium. This case therefore seems to represent a new and very rare form of glomerular involvement in multiple myeloma.