Fibrillary Glomerulopathy With Immune Complex Deposition and Superimposed Crescentic Glomerulonephritis in an Octogenarian

Fibrillary glomerulopathy is an uncommon cause of progressive kidney disease, and the development of superimposed crescentic glomerulonephritis creates a particularly difficult therapeutic challenge.We report an 84-year-old woman with progressive kidney dysfunction, persistent hematuria, and proteinuria.Over 12 months, serum creatinine increased from 0.99 mg/dL to 2.52 mg/dL, with estimated glomerular filtration rate declining from 57 mL/min/1.73m² to approximately 18 mL/min/1.73m².Serologic evaluation, including antinuclear antibody, antineutrophil cytoplasmic antibody, and complement levels, was unrevealing, and evaluation for monoclonal gammopathy was negative.Kidney biopsy demonstrated DNAJB9-negative fibrillary glomerulopathy with superimposed focal crescentic glomerulonephritis.The patient was initially treated with prednisone 80 mg daily, and avacopan was started at a dose of 30 mg twice a day two weeks after initiation of prednisone therapy.The prednisone dose was rapidly tapered, and avacopan was subsequently used as a glucocorticoid-sparing strategy.At 12 months, kidney function remained stable, with serum creatinine of 1.97 mg/dL without progression to dialysis-dependent kidney failure.Early biopsy and individualized immunosuppressive therapy are critical, and emerging agents such as avacopan may offer glucocorticoid-sparing benefits in selected cases.