Abstract: SA-PO0783
IgM Variant of Proliferative Glomerulonephritis with Monoclonal Immunoglobulin Deposits: A First Case Report from Thailand
Session Information
- Glomerular Diseases: Lupus Nephritis, Monoclonal Gammopathy-Related Disease, and Transplantation
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Laorwarakoon, Monthorn, Faculty of Medicine Vajira Hospital, Bangkok, Thailand
- Jaturapisanukul, Solos, Faculty of Medicine Vajira Hospital, Bangkok, Thailand
Introduction
Proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) is a rare immune complex–mediated glomerulonephritis characterized by monotypic immunoglobulin deposition in kidney. The IgM variant is particularly uncommon and remains poorly characterized.
Case Description
A 77-year-old Asian man with well-controlled hypertension, type 2 diabetes mellitus, and chronic kidney disease stage G3 presented with foamy urine, dyspnea, and peripheral edema. Laboratory evaluation showed subnephrotic-range proteinuria(UPCR 2.52 g/g), bland urinary sediment, preserved kidney function(eGFR of 75.8 mL/min/1.73 m^2), and serum albumin of 3.7 g/dL. Serologic testing for HIV, HBV, HCV, syphilis, cryoglobulin, and complement abnormalities was unremarkable. Serum protein electrophoresis and immunofixation showed no detectable monoclonal gammopathy, and the serum free light chain ratio was normal. Kidney biopsy showed diffuse mesangial proliferative glomerulonephritis with mild interstitial fibrosis and tubular atrophy. Immunofluorescence revealed granular mesangial deposits positive for IgM, C3, and lambda light chain restriction. Electron microscopy showed electron-dense deposits in mesangium, with occasional subendothelial deposits. These findings supported a diagnosis of IgM variant PGNMID. An angiotensin II receptor blocker was initiated, followed by rituximab at a dose of 1 g for two cycles. At follow-up, patient had complete resolution of edema and stable kidney function.
Discussion
This case highlights a rare IgM variant of PGNMID from Thailand, occurring in the absence of a detectable clone or circulating monoclonal protein. Kidney biopsy with immunofluorescence and electron microscopy remains essential for diagnosis. Although optimal treatment remains uncertain, rituximab may be considered in selected patients with IgM variant PGNMID because of a possible underlying pathologic B-cell origin that may contribute to disease pathogenesis. Long-term follow-up is required to assess the durability of renal response and risk of progression.
IF showed 2+ granular staining for IgM, 1+ staining for Lambda and negative for Kappa
mesangial hypercellularity on PAS