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Abstract: SA-PO1079

Differences in Renal Histopathology Between PR3-ANCA-Associated Vasculitis and MPO-ANCA-Associated Vasculitis

Session Information

Category: Pathology and Lab Medicine

  • 1502 Pathology and Lab Medicine: Clinical

Authors

  • Wester Trejo, Maria, Leiden University Medical Center, Leiden, Netherlands
  • Van Daalen, Emma, Leiden University Medical Center, Leiden, Netherlands
  • Wolterbeek, Ron, Leiden University Medical Center, Leiden, Netherlands
  • Ferrario, Franco, San Gerardo Hospital, Monza, Italy
  • Joh, Kensuke, Tohoku University Graduate School of Medicine, Sendai, Japan
  • Noel, Laure-Helene, Necker Hospital, Paris, France
  • Ogawa, Yayoi, Hokkaido Renal Pathology Center, Sapporo, Japan
  • Wilhelmus, Suzanne, Pathan, Rotterdam, Netherlands
  • Ball, Miriam Jane, Medical University of Vienna, Vienna, Austria
  • Honsova, Eva, Institute for Clinical and Experimental Medicine, Prague, Czechia
  • Hruskova, Zdenka, Charles University and General University Hospital, Prague, Czechia
  • Kain, Renate, Medical University of Vienna , Vienna, Austria
  • Kronbichler, Andreas, Medical University Innsbruck, Innsbruck, Austria
  • Lindhard, Kristine, Rigshospitalet, Copenhagen, Denmark
  • Puéchal, Xavier, Hôpital Cochin, Paris, France
  • Salvatore, Steven, Weill Cornell Medical College, New York, New York, United States
  • Szpirt, Wladimir M., Rigshospitalet, Copenhagen, Denmark
  • Tesar, Vladimir, Charles University and General University Hospital, Prague, Czechia
  • Bruijn, Jan A., Leiden University Medical Center, Leiden, Netherlands
  • Bajema, Ingeborg M., Leiden University Medical Center, Leiden, Netherlands
Background

Clinical and experimental data suggest a pathogenic role for antineutrophil cytoplasmic antibodies (ANCA) in ANCA-associated glomerulonephritis (AAGN), with possible differences between anti-myeloperoxidase (MPO)- and anti-proteinase 3 (PR3)-ANCA. The aim of this study was to investigate differences in histopathological profile between MPO- AAGN and PR3-AAGN. Additionally, the effect of ANCA serotype on long-term renal outcome was examined.

Methods

135 patients from 10 centers worldwide (Europe, North-America, Asia) with AAGN who underwent a diagnostic renal biopsy between 1991 and 2011 were included. Biopsies were scored on a secured website. Data on demographics, renal outcome and diagnostic delay were collected retrospectively.

Results

50 patients were positive for PR3-ANCA and 73 for MPO-ANCA; 12 patients were either double-positive or negative. At diagnosis, patients with MPO-AAGN were significantly older (64.5±12.0 years) than those with PR3-AAGN (57.4±12.8 years). Mean diagnostic delay did not differ between groups. MPO-ANCA-positive patients showed less focal class and more mixed class than PR3-ANCA-positive patients (P=0.04). MPO-AAGN biopsies showed significantly more interstitial fibrosis and tubular atrophy (IFTA) than PR3-AAGN biopsies (P=0.04). On immunofluorescence, MPO-AAGN showed less C3-positive staining than PR3-AAGN (P=0.02). We found no association between ANCA serotype and death, renal relapse or development of end-stage renal disease.

Conclusion

In this large, international, multicenter cohort, we found a different histopathological profile in MPO-AAGN compared to PR3-AAGN, characterized by a lower percentage of focal and higher percentage of mixed histopathological class, more IFTA and less C3 in MPO-AAGN. These findings could not be explained by differences in diagnostic delay between groups and therefore support a difference in pathogenesis between MPO- and PR3-AAGN.