Abstract: SA-PO0710
Revisiting the Diagnosis: Fibrillary Glomerulonephritis in a Patient Initially Diagnosed with Anti-GBM Disease
Session Information
- Glomerular Diseases: Complement-Mediated Glomerulopathies and Infection-Related GN
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
- Galicia Garcia, Gabriela, Columbia University, New York, New York, United States
- Navarro Torres, Mariela, Columbia University, New York, New York, United States
Introduction
Rapidly progressive glomerulonephritis (RPGN) is marked by rapid loss of kidney function and extensive crescent formation. Anti–glomerular basement membrane (anti-GBM) disease is a common cause of RPGN, identified by linear IgG deposition and positive serum anti-GBM antibodies. Fibrillary glomerulonephritis (GN) often presents with nephrotic-range proteinuria and progressive kidney dysfunction, rarely presenting as RPGN. We describe a case of fibrillary GN initially diagnosed as anti-GBM disease.
Case Description
A 73-year-old woman with hypertension presented with dysuria. Initial workup revealed a UTI, severe AKI (baseline sCr 0.92 mg/dL, peak 4.24 mg/dL), and 6.8 g/g of proteinuria. Anti-GBM antibodies, ANCA, ANA, and anti-dsDNA antibodies were negative, and complement levels were normal. Kidney biopsy revealed 40% crescents, with IgG linear staining along capillary walls on immunofluorescence, which led to a diagnosis of anti-GBM disease. She was treated with oral cyclophosphamide and ten sessions of plasma exchange (PLEX), with creatinine improving to 1.4 mg/dL at discharge.
A month later, she returned with AKI and received ten additional sessions of PLEX. Serum anti-GBM antibodies remained negative. Five years later, worsening kidney function (sCr 2.7 mg/dL) prompted a repeat kidney biopsy, which revealed 12/25 globally sclerosed glomeruli and 35% IFTA. Electron microscopy (EM) showed aggregates of short, non-branching, randomly arranged fibrils and positive DNAJB9 stain, wtih negative staining by Congo-red, consistent with fibrillary GN. She was managed with RAS inhibition and SGLT2i. Her creatinine was 1.9mg/dL with 1.5g/g of proteinuria at last follow-up.
Discussion
This case highlights the diagnostic challenge of fibrillary GN when EM or DNAJB9 staining is delayed or unavailable. In this case, the initial biopsy did not show fibrils on EM, and DNAJB9 stain was not yet clinically available. The presence of linear IgG staining may have confounded the diagnosis. Pseudolinear IgG staining due to colocalization of the DNAJB9 protein with IgG in the glomerular capillary wall is a rare finding in fibrillary GN. To our knowledge, this is one of five cases previously reported. This case underscores the importance of considering fibrillary GN in the differential diagnosis of RPGN with a linear IgG pattern, particularly in patients with negative anti-GBM antibody.