Abstract: TH-PO0826
Silent Fibrils: When DNAJB9 Cracks the Diagnosis in a Patient Without Significant Proteinuria
Session Information
- Glomerular Case Reports: Potpourri
November 06, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Ebrahimi, Niloufar, Loma Linda University Medical Center, Loma Linda, California, United States
- Baxi, Pravir V., Rush University Medical Center, Chicago, Illinois, United States
- Abdi Pour, Amir, Loma Linda University Medical Center, Loma Linda, California, United States
- Whittier, William Luke, Rush University Medical Center, Chicago, Illinois, United States
Introduction
Fibrillary glomerulonephritis (FGN) is a rare glomerular disease typically presenting with nephrotic range proteinuria and characterized by non-amyloid fibrillary deposits on kidney biopsy. DNAJB9 staining has recently improved diagnostic precision.
Case Description
A 72-year-old woman with obesity, hypertension, chronic foot drop, DVT on anticoagulation, and gout was referred for progressive CKD. She reported 70 lbs of unintentional weight loss over one year. Her creatinine increased from 1.3 to 2.3 mg/dL over six months. Despite discontinuing losartan and spironolactone, creatinine remained elevated. Urine sediment was bland with trace protein, urine protein creatinine ratio was 242 mg/g, and 24-hour urine collection for protein revealed 0.2 g/day. Other laboratory results showed normal serum albumin (3.6 g/dL), negative ANA and ANCA, normal complements, negative HIV, hepatitis B/C serologies, and unremarkable serum and urine protein electrophoresis. Kidney ultrasound showed bilaterally echogenic kidneys without hydronephrosis. A biopsy (Figure) revealed FGN with positive glomerular staining for DNAJB9 without tubulointerstitial or vascular fibrils. Malignancy workup, including CT imaging, mammography, and colonoscopy, was negative. The patient was managed with RAS blockade and rituximab, and kidney function has stabilized over the next 12 months.
Discussion
This case highlights a subtle presentation of FGN with minimal proteinuria and non-specific symptoms. Kidney biopsy is most often considered due to the degree of proteinuria, but in this case, unexplained progressive CKD without proteinuria was the indication. In a cohort of 64 patients with FGN, notably, 8% of patients had proteinuria less than 1 g/day, while 38% had proteinuria between 1 and 3 g/day. DNAJB9 staining is a highly specific and sensitive immunohistochemical marker in diagnosing FGN from similar entities, and in our case, was a surprising feature in the glomeruli, given the atypical clinical presentation.
Figure. Pathology Results from Kidney Biopsy