Proliferative Glomerulonephritis with Monoclonal IgG Deposits

This renal biopsy from a 57-year-old male with acute renal failure, hematuria, and nephrotic-range proteinuria shows a proliferative glomerulonephritis (A) with IgG kappa-restricted deposits by immunofluorescence. These findings are consistent with the entity known as proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID). Approximately 30% of patients with these renal biopsy findings prove to have an associated monoclonal immunoglobulin in the serum. However, the underlying etiology in the majority of these cases is undetermined as most do not have evidence of infection, autoimmune disease or hematologic malignancy.