Proliferative glomerulonephritis with monoclonal immunoglobulin deposits

Abstract

Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) is a relatively recently described form of glomerulonephritis that mimics immune-complex-type glomerulonephritis on light microscopy and electron microscopy. However, by immunofluorescence, the glomerular deposits are monotypic, staining for a single light chain isotype and a single gamma heavy chain subclass, most commonly IgG3 kappa. PGNMID is classified as a monoclonal gammopathy of renal significance - lesion characterized by non-organized deposits in patients who do not have systemic lymphoma or multiple myeloma. Despite the monotypic nature of glomerular deposits, only a small subset of patients has a detectable serum monoclonal immunoglobulin, and hematologic malignancy is rare. Furthermore, PGNMID does not appear to represent a premyelomatous condition in most patients. The disease mainly affects adults and is slightly more common in females. Most patients present with nephrotic-range proteinuria and hematuria with or without renal insufficiency. Prognosis is variable, with nearly a quarter of patients progressing to ESRD within 2.5 years despite immunomodulatory therapy. Early recurrence in the renal allograft is observed in most patients. The pathogenesis of PGNMID remains elusive.