#3041 Dnajb9 Positive Primary Fibrillary Glomerulonephritis: Treatment With Corticosteroid Pulses Experience

Abstract

Background and Aims Fibrillary glomerulonephritis (FGN) is a rare histological pattern. Electron microscopy is needed for diagnostic confirmation where predominantly mesangial fibrils are observed. To support the diagnosis; DNAJB9 is a biomarker that is 100% sensitive and 100% specific for FGN. To date, there is no defined therapeutic approach. Various immunosuppressants have been implemented to treat FGN showing poor renal response and approximately 50% progression to chronic kidney disease. Method Ambispective observational study. A protocol based on a bibliographic review was developed. The protocol included an induction therapy with methylprednisolone pulses (MTP), 500 mg a day for three days. Followed by oral prednisone at a dose of one mg/kg with an individual titration period considering the clinical evolution. Demographic, clinical, and pathological variables were extracted from the electronic health record. Results Case 1. Seventy-eight-year-old female. History of arterial hypertension (HT) treated with an angiotensin-converting enzyme inhibitor (ACEi). She debuted with a nephrotic syndrome characterized by proteinuria of 15 grams/day, hypoalbuminemia, and altered kidney function with creatinine (Cr) of 2.7 mg/dL. Secondary causes were rule out. The kidney biopsy showed mesangial expansion with mesangial deposition of IgG and C3 on the immunofluorescence. Congo red was negative. Positivity for DNAJB9 was observed. The electron microscopy (EM) showed 20-nanometer fibrils in the mesangium. The patient was initiated on the treatment protocol with a subsequent reduction of prednisone over a period of 24 weeks. Complete remission, defined as proteinuria <0.5g/day and reduction > 50% of Cr was achieved after 20 weeks of treatment. Case 2. Forty-seven-year-old female with a history of hypertension treated with ACEi. The patient presented with proteinuria 3.5g/d with a normal kidney function. Secondary causes were rule out. The kidney biopsy showed mesangial thickening with IgG, C3, C1q, Kappa, and lambda positivity on immunofluorescence. Congo red was negative. DNAJB9 was positive. An electron microscopy study showed randomly arranged mesangial fibrils. The treatment protocol was started. Prednisone was titrated over a period of 20 weeks. Partial remission was observed, defined by >50% reduction of proteinuria. Kidney function remained preserved. Conclusion Induction treatment based on steroid pulses followed by prednisone titration in patients with FGN with predominantly mesangial compromise was associated with a substantial reduction of proteinuria and stabilization of kidney function.