DNAJB9 Fibrillary Glomerulonephritis Following Rituximab-Based Therapy: A Case of Temporary Renal Recovery.

A 63-year-old man, with no relevant history, developed acute kidney injury with an elevated serum creatinine level of 314 µmol/L associated with hypertension, a nephrotic syndrome, without hematuria. Kidney biopsy revealed a glomerular-specific deposition of DnaJ homolog subfamily B member 9 (DNAJB9). Fibrillary glomerulonephritis was diagnosed. The patient received corticosteroids, rituximab (1 g at day 1 and day 15; 1 g at month 6), and nephroprotection. Kidney dysfunction initially worsened (creatinine 513 µmol/L), and peritoneal dialysis was initiated. Partial renal function recovery was observed after the rituximab-maintenance dose, allowing dialysis discontinuation for one year (October 2023 to September 2024). In some studies, rituximab-based therapy was associated with stabilization of disease progression. As observed in our case, it could be considered on a case-by-case basis, with a possible benefit for partial treatment response and time-limited disease control.