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Abstract: TH-PO941

A Case of Fibrillary Glomerulonephritis with a High Level of Myeloperoxidase-ANCA

Session Information

Category: Trainee Case Report

  • 1201 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

  • Asakawa, Tomohiko, Suwa Central Hospital, Chino, NAGANO, Japan
  • Araki, Makoto, Suwa Central Hospital, Chino, NAGANO, Japan
Introduction

Gross hematuria with renal dysfunction suggests the possibility of rapidly progressive glomerulonephritis (RPGN) and requires urgent attention. Anti-neutrophil cytoplasmic antibody (ANCA)- associated vasculitis (AAV) represents RPGN and is characterized by elevated serum ANCA levels and pauci-immune crescentic glomerulonephritis. But it is well known that the presence of a high titer of ANCA does not imply the presence of disease.

Case Description

A 71 year-old woman was admitted with the chief complaint of gross hematuria. Her laboratory values indicated a Cr 1.52 mg/dl and advanced proteinuria of 7.5 g/g・Cr. There was no fever, and her white blood cells were within the normal range. Further examination revealed a high myeloperoxidase (MPO) -ANCA level (96.6 U/ml, normal < 3.5), no monoclonal proteins, and normal complement levels. Thus, a renal biopsy was performed; it showed mesangial proliferation in all 13 glomeruli and crescents formation in 5 glomeruli. Immunofluorescent staining was positive for IgG, C3, and C1q. The deposition of fibrils was recognized in the glomerulus by electron microscopy. In addition, immunohistochemical staining for DNA-J heat shock protein family member B9 (DNAJB9) was strongly positive in the glomerulus. These results indicated the presence of fibrillary glomerulonephritis (FGN). Hence, we performed induction therapy with prednisolone and intravenous cyclophosphamide, and subsequently the patient’s renal function improved.

Discussion

From the histological findings, it was considered that the patient’s renal dysfunction was caused by either FGN alone or from concomitant AAV and FGN. FGN is a rare disease found in 1% of renal biopsies. Although renal damage of FGN is caused by immune complexes, only approximately 17% of the cases are positive for M-protein, and 2% have hypocomplementemia. As the diagnosis required electron microscopy examination, some cases may have been overlooked. DNAJB9, a recently discovered histological marker of FGN, is expected to improve diagnosic accuracy and therefore increase the number of reported cases.