Kidney Week

Abstract: FR-PO1154

Atypical Anti-GBM to Proliferative Glomerulonephritis with Monoclonal Immunoglobulin Deposits in a Kidney Allograft

Session Information

• Transplantation: Clinical - Transplant Access, Recipient Evaluation, Living Donors, Pregnancy, and More
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• 2002 Transplantation: Clinical

Authors

• Obeidat, Yasin, Cleveland Clinic, Cleveland, Ohio, United States

Yasin Obeidat, MD

• Mahfouz, Ratib Talal, Cleveland Clinic, Cleveland, Ohio, United States

Ratib Talal Mahfouz, MD

• Dweik, Loai, Cleveland Clinic, Cleveland, Ohio, United States

Loai Dweik, MD

• Owoyemi, Itunu O., Cleveland Clinic, Cleveland, Ohio, United States

Itunu O. Owoyemi, MBBS, FASN

• Huang, Yuan, Cleveland Clinic, Cleveland, Ohio, United States

Yuan Huang, MD, PhD

• Fatica, Richard A., Cleveland Clinic, Cleveland, Ohio, United States

Richard A. Fatica, MD

Introduction

Proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID) is a rare entity within the spectrum of MGRS characterized by monotypic immunoglobulin (Ig) deposition, most commonly IgG3 kappa. PGNMID recurs in up to 90% of kidney allografts, with early graft loss. Atypical anti-GBM nephritis — linear GBM staining for monotypic Ig without crescents and with negative circulating anti-GBM antibodies — also recurs in transplants. The overlap of these pathologies in a transplant recipient is not clear.

Case Description

A man in his 60s with ESKD secondary to sclerosing glomerular lesions (likely past glomerulonephritis), chronic hematuria, and positive pANCA underwent deceased donor kidney transplant (DDKT). The first allograft with primary nonfunction showed acute tubular injury. After a second DDKT, 3-month biopsy was unremarkable. A 6 month surveillence biopsy revealed subclinical Banff 1B ACR with a single segmental necrosis and crescent formation, treated with thymoglobulin and IV Methylprednisolone. A 10-month follow up biopsy showed fibrous proliferation within Bowman's capsule, focal global glomerulosclerosis, and linear IgA GBM staining with equal kappa/lambda — suggestive of atypical anti-GBM nephritis (circulating anti-GBM negative). Subsequent for-cause biopsy for AKI with gross hematuria and subnephrotic proteinuria demonstrated proliferative GN with endocapillary hypercellularity, persistent linear IgA/kappa/lambda GBM staining, new mesangial monoclonal IgG kappa staining and electron-dense deposits. Serology revealed new pANCA/MPO positivity with negative anti-GBM antibodies. The patient was initially managed as double-positive ANCA/anti-GBM disease with IVMP and plasmapheresis. Ig subclass analysis then revealed IgG3 kappa restriction, establishing PGNMID. He was started on CyBorD (cyclophosphamide, bortezomib, daratumumab, dexamethasone) with recovery of kidney function.

Discussion

This case illustrates evolution from atypical anti-GBM nephritis with polyclonal immunoglobulin to PGNMID with IgG3 kappa restriction in a kidney allograft, complicated by concurrent ANCA/MPO positivity — an exceedingly rare combination. It underscores the importance of comprehensive immunofluorescence evaluation including IgG subclass and light chain restriction analysis in transplant biopsies with atypical staining patterns. Further investigation into the relationship between atypical anti-GBM nephritis and PGNMID is warranted.