Nodular glomerulosclerosis secondary to mu heavy chain deposits

mu heavy chain deposition disease is very rare. We report the first case of glomerulonephritis in a woman without evidence of hematopoietic malignancy. Nodular glomerulosclerosis and monotypic mu heavy chain mesangial deposits were identified by immunofluorescence without kappa or lambda deposits. Electron microscopy showed fibrillar mesangial deposits of 16-18 nm in diameter. Serum immunoglobulins, cryoglobulins, serum immunoelectrophoresis, and immunofixation, bone marrow biopsy, and Bence Jones proteins in urine were negative. The patient has stable renal disease and is free of malignancy 6 years after the initial occurrence of proteinuria.