Abstract: TH-PO0776
A Rare Case of Monoclonal IgG1-Lambda Atypical Anti-Glomerular Basement Membrane (GBM) Disease
Session Information
- Glomerular Case Reports: Membranous, PGN, GBM, and More
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Al Zoubi, Sarah, University of Illinois Chicago, Chicago, Illinois, United States
- Levine, Jerrold S., University of Illinois Chicago, Chicago, Illinois, United States
- Albadri, Sam, Mayo Clinic Minnesota, Rochester, Minnesota, United States
- Cornell, Lynn D., Mayo Clinic Minnesota, Rochester, Minnesota, United States
Introduction
Atypical Anti-GBM is a rare subset of anti-GBM disease characterized by linear deposition of immunoglobulin (Ig) without the presence of circulating anti-GBM antibodies. The deposited Ig may be either polyclonal or monoclonal. Here, we present a case of atypical anti-GBM with monoclonal IgG1-lambda deposits.
Case Description
A 34 year old female presented with recurrent gross hematuria and subnephrotic proteinuria. A few months prior, she had acute kidney injury, improved with steroids given for presumed acute interstitial nephritis (Creatinine: 3.0 mg/dL, baseline: 0.9 mg/dL). At presentation, her labs were remarkable for creatinine of 1.4 mg/dL, microscopic hematuria, and subnephrotic proteinuria (UPCR; 1.45 g/g). A secondary workup including serum and urine immunofixation was negative. Kidney biopsy (Figure 1) revealed endocapillary proliferation and fibrocellular crescents on light microscopy (LM), and linear staining for IgG with monoclonal IgG1 and lambda restriction on immunofluorescence (IF). The patient was subsequently started on anti-plasma cell chemotherapy.
Discussion
Atypical anti-GBM, which occurs in around 10% of anti-GBM disease, usually presents with heavier proteinuria, less frequent lung involvement, and better renal survival than typical cases. Kidney biopsy typically shows a proliferative pattern without the presence of crescents. IF is crucial to detect monoclonality, which is present in half of patients. Neither the target antigens nor optimal treatment has been established, although patients with monoclonal atypical anti-GBM should receive clonal B cell chemotherapy. Our patient had subnephrotic proteinuria and crescents on LM, findings not commonly observed in atypical anti-GBM cases. IF confirmed monoclonal IgG1-Lambda anti-GBM disease. In conclusion, careful kidney biopsy analysis is essential in cases of atypical anti-GBM disease, since monoclonality requires treatment with clonal B cell chemotherapy.