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Abstract: TH-PO709

A Case of Rapidly Progressive Glomerulonephritis due to Superimposed IgA Nephropathy on Collagenofibrotic Glomerulopathy

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Ochiai, Shoko, Miyazaki Daigaku, Miyazaki, Miyazaki, Japan
  • Kikuchi, Masao, Miyazaki Daigaku, Miyazaki, Miyazaki, Japan
  • Kaikita, Koichi, Miyazaki Daigaku, Miyazaki, Miyazaki, Japan
  • Fujimoto, Shouichi, Miyazaki Daigaku, Miyazaki, Miyazaki, Japan
Introduction

Collagenofibrotic glomerulopathy (CFG) is a rare disease characterized by the accumulation of type III collagen in the glomerulus. CFG and IgA nephropathy (IgAN) may coexist coincidentally, but there have been no reports presenting rapidly progressive glomerulonephritis (RPGN). Here, we report the case that developed in RPGN and was diagnosed with active IgAN accompanied by CFG.

Case Description

A 69-year-old Japanese woman complained of new-onset fatigue and generalized edema lasting one month. She had a history of rheumatoid arthritis for about 20 years and had been administered etanercept, a TNFα inhibitor, for eight years. Her serum creatinine (SCr) level used to be around 1.5 mg/dL. On admission, She exhibited gross hematuria, an elevated SCr (5.8 mg/dL), a decreased serum albumin (2.63 g/dL), a weight gain (+10 kg), and was clinically diagnosed with RPGN and nephrotic syndrome. Histological examination revealed active IgAN with positive KM55(galactose deficient(Gd)-IgA1) and superimposed CFG. She temporarily needed hemodialysis, but with steroid pulse therapy and cyclophosphamide, her SCr improved to 2.66 mg/dL, and hematuria was also resolved.

Discussion

This is the first report of RPGN caused by IgAN superimposed on CFG. In IgAN, IgA deposition in the capillary wall have been reported to have a poor renal prognosis. In this case, the presence of type III collagen in the mesangial region promoted IgA deposition in the capillary wall and induced RPGN. Furthermore, this is the first case in which etanercept induced IgA nephropathy with Gd-IgA1. The mechanism of action of TNFα inhibitor-induced IgAN may be the generation of anti-drug antibodies to the glycan structures of the TNFα inhibitors. This cross-reacts with Gd-IgA1 and forms a large antigen-antibody complex, and then may have caused IgAN. Despite the rare and complex diseases, we believe the appropriate interpretation of renal biopsy findings contributed to effective treatment and favorable renal outcomes.