A Case of Switch from C3 Glomerulonephritis to Proliferative Glomerulonephritis with Monoclonal IgG Deposits

Monoclonal immunoglobulins have been implicated in the development of C3 glomerulonephritis (C3GN) and Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID). We report a 58-year-old female who showed a switch from C3GN to PGNMID. She presented with mild proteinuria and normal renal function for the first time. Her renal biopsy showed a severe mesangial proliferation with isolated C3 deposits, thus being diagnosed as C3GN. Two years later, her condition became serious. Repeat renal biopsy showed a membranoproliferative glomerulonephritis with deposition of the kappa light chain of IgG3 in the glomeruli. She was diagnosed with proliferative glomerulonephritis with monoclonal IgG deposits (IgG3-kappa). This case demonstrates that there are several types of monoclonal gammopathy (MGP)-associated glomerulonephritis, and they can switch among each other in some patients.