Recurrent proliferative glomerulonephritis with monoclonal IgG deposits of IgG2λ subtype in a transplanted kidney: a case report.

Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMID) is a recently described disease entity. In the kidney transplantation literature, only 6 recurrent and 2 de novo PGNMID cases, including 7 of the IgG3 subclass (6 with κ light chain and 1 with λ light chain) and 1 of the IgG1 subclass (λ light chain), have been described to date. We describe a 52-year-old man with end-stage renal disease whose primary glomerular disease had been suggested to be membranoproliferative glomerulonephritis. The patient underwent living related donor kidney transplantation and presented with proteinuria, hematuria, and decreased kidney function at 4 months posttransplantation. Biopsy of the transplanted kidney showed diffuse endocapillary proliferative glomerulonephritis. Immunofluorescence microscopy showed prominent granular glomerular staining for IgG, C3, and λ light chain, with IgM, IgA, and κ light chain undetectable. Immunofluorescence staining for IgG subclass showed signal for IgG2 only. Retrospective analysis of the native kidney biopsy specimen also showed the same monoclonal glomerular staining for the IgG2λ subtype. These findings led us to the diagnosis of PGNMID of the IgG2λ subtype as both the primary glomerular disease and recurrent disease in the transplanted kidney. Recurrence was treated with high-dose prednisolone, which decreased proteinuria, hematuria, and serum creatinine level. The case demonstrates that PGNMID of the IgG2λ subtype also can recur in the transplanted kidney.