Fibrillary glomerulonephritis: clinicopathological characteristics and treatment in a spanish tertiary center

Fibrillary glomerulonephritis (FGN) has a poor prognosis and lacks standardized treatment. In this study, we describe clinicopathological characteristics, clinical course, and management of patients with FGN at our center.

A retrospective cohort study of 13 patients diagnosed with FGN by positive DNAJB9 at kidney biopsy between 2019 and 2024. Demographic data, comorbidities, laboratory values, histopathological findings, and treatments were collected, Complete remission was defined as proteinuria <500 mg/g with normal renal function; partial remission as >50% reduction in proteinuria to <2000 mg/g with stable renal function; and no remission as absence of improvement, progression to end-stage kidney disease (ESKD), or death.

The mean age was 61.4 years, 69,2% male, median proteinuria of 2318 mg/g (38% nephrotic range) and serum creatinine 1.64 mg/dL, Histopathological findings: 29% global glomerulosclerosis. The most frequent pattern was membranoproliferative (61.6%), followed by mesangial (30.8%) and membranous in 1 patient (7.7%), Hypoalbuminemia (<3 g/dL) was associated with worse prognosis (HR 6.52, p = 0.04); proteinuria >3500 mg/g and creatinine showed non-significant trends. Immunosuppression was given in 84.6% of patients: rituximab (RTX) (61.5%), RTX + mycophenolate (7.7%), sequential RTX followed by ocrelizumab and obinutuzumab (7.7%), and corticosteroids alone (7.7%). Partial remission was achieved in 30.8%, all within the exclusive RTX group, A total of 38.4% progressed to ESKD or death.

In our study, FGN showed poor prognosis and partial response to rituximab. FGN with hypoalbuminemia had worse outcomes. Prospective studies and larger cohorts are needed to validate these findings and optimize its management.