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Kidney Week

Abstract: TH-PO520

Fibrillary GN vs Amyloidosis on Renal Biopsy: Dilemma on How to Treat

Session Information

  • Trainee Case Reports - I
    October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Reports

  • 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

  • Gandhi, Pulkit, Brown University, Providence, Rhode Island, United States
  • Tang, Jie, University Medicine; Brown University, West Roxbury, Massachusetts, United States
Introduction

Glomerular disease may be associated with fibrillary deposits on glomerular basement membrane or mesangium. Frequently there is a clear distinction between Amyloidosis and non-amyloid fibrillary deposits based on the fibril size on electron microscopy and reaction to Congo red stain. But occasionally we see overlapping patterns. Here we present a unique case of glomerular deposition disease with an overlapping pattern, where the kidney biopsy showed Congo red positivity, but the fibril sizes were larger than as expected in amyloidosis. Patient presented with acute kidney injury (AKI) and clinical evidence of glomerulonephritis (GN).

Case Description

A 58 y/o male with medical history of hepatitis C status post treatment with Harvoni in 2015 with negative viral PCR (9/2016), well controlled type 2 DM (HbA1C 5.2), well controlled HTN, Chronic kidney disease stage III A presented as an outpatient consult for worsening serum creatinine. The serum creatinine rose from a baseline of 1.1 mg/dl to 3.2mg/dl in a period of 3 months. 24hr urine showed significant proteinuria measured at 2682 mg. His urine sediment showed microscopic hematuria, but no dysmorphic features. Serologic studies showed elevated kappa/lambda ratio at 2.52 but normal serum and urine protein electrophoresis, normal C3 and C4 complement levels, and negative anti neutrophil cytoplasmic antibody. Patient underwent renal biopsy, which showed glomerulopathy - mesangioproliferative pattern, with mesangial and subendothelial fibrillary deposits. The fibrils measured 14.8 nm in diameter, and these deposits were congo red positive, and were reactive for IgG (predominant IgG4) and C3. The stain for protein A was negative. In addition, there were advanced chronic changes noted in the parenchyma, including global and segmental glomerulosclerosis (52% of glomeruli) and significant tubulointerstital fibrosis (60% of the cortex). Considering atypical findings on renal biopsy and underlying significant tubulointerstitial fibrosis, we decided to treat him with mycophenolate and prednisone instead of more aggressive chemotherapy for amyloidosis. He responded well as his serum creatinine trended down from 3.2 mg/dl to 1.5 mg /dl in 6 months.

Discussion

We believe this is the first case of glomerular deposition disease with overlapping features of amyloidosis and fibrillary GN, who responded well to a rather conservative regimen of MMF with steroid.