Cohen, Scott

Abstract Background: Fibrillary glomerulonephritis (FGN) is a rare immune-mediated glomerular disease characterized by glomerular fibrillar deposits and historically associated with poor kidney outcomes. Despite recent diagnostic advances, including DNAJB9 immunohistochemistry, the clinical spectrum, prognostic factors, and optimal management of FGN remain incompletely defined. Methods: We conducted a retrospective cohort study of patients with biopsy-proven FGN identified through the Cleveland Clinic Kidney Biopsy Epidemiology Project between January 2015 and March 2023. Results: Thirty patients met inclusion criteria. The cohort was predominantly female (70%) and white (86%), with a median age of 64 years. At the time of kidney biopsy, all patients had hypertension and acute or chronic kidney disease. Additional features included hematuria (76%), proteinuria (60%), and nephrotic syndrome (48%). Monoclonal protein was detected in 20% of cases. During a mean follow-up of 24 months (range 0–70 months; n = 13), 23% achieved partial remission, 23% had persistent disease, and 53% progressed to end-stage kidney disease (ESKD). Higher serum creatinine at biopsy was the only variable associated with progression to ESKD. Conclusion: FGN remains a rare glomerular disease with substantial risk of progression to kidney failure. This single-center cohort highlights the heterogeneous clinical presentation and generally poor kidney outcomes of FGN in the modern diagnostic era. Larger, multicenter studies are needed to refine prognostic stratification and guide evidence-based management strategies.