Relapsing proliferative glomerulonephritis with monoclonal IgG deposits showing circumferential crescentic glomerulonephritis

Several types of glomerulonephritis associated with dysproteinemia, such as AL-amyloidosis, light-and heavy-chain deposition disease, and type 1 cryoglobulinemic glomerulopathy, demonstrate monoclonal immunoglobulin deposition. Progressive glomerulonephritis with monoclonal IgG deposits (PGNMID) is also known to feature monoclonal glomerular deposits, but most of these cases occur without underlying disease. We here report a case of recurrent PGNMID that developed as diffuse cellular crescentic glomerulonephritis 8 years after an initial diagnosis of membranopro-liferative glomerulonephritis (MPGN). Determination of the monoclonality of the deposited immunoglobulin is vital to make the correct diagnosis and enable an early administration of aggressive immunosuppressive therapy.