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 κ light chain of IgG3 in the glomeruli. She was diagnosed with proliferative glomerulonephritis with monoclonal IgG deposits (IgG3-κ). This case demonstrates that there are several types of monoclonal gammopathy (MGP)-associated glomerulonephritis, and they can switch among each other in some patients.