Proliferative glomerulonephritis with monoclonal IgG deposits recurs or may develop de novo in kidney allografts.

Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMIGD) is a recently recognized glomerular disease. Light microscopy usually resembles membranoproliferative glomerulonephritis. Glomerular deposits are mostly IgG3 κ; however, unlike in the usual forms of monoclonal immunoglobulin deposition disease, extraglomerular deposits are absent. If PGNMIGD is secondary to the glomerular deposition of circulating monoclonal IgG, it is expected to recur in kidney allografts with the same pattern of monoclonal IgG deposition. We reviewed our kidney biopsy files between January 1, 2003, and January 4, 2010, and identified 21 biopsy specimens with PGNMIGD, mostly with glomerular IgG3 κ deposits. Of the 21 biopsy specimens, 4 were from kidney allografts; 2 were recurrent and the other 2 were de novo diseases. Recurrent PGNMIGD develops rapidly, causing proteinuria. This rapid recurrence of PGNMIGD in kidney allografts provides further proof that PGNMIGD is secondary to the glomerular deposition of circulating monoclonal IgG.