Purpose of review: This review discusses the findings of studies validating the histopathological classification of antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, which was devised in 2010 by an international working group of pathologists and nephrologists in collaboration with the European Vasculitis Society.
Recent findings: So far, eight studies have validated the histopathological classification of ANCA-associated glomerulonephritis. The studies came from Japan, China, Australia, the United States, the Netherlands, and Turkey. These validation studies confirmed that the histopathological classification of ANCA-associated glomerulonephritis is of predictive value for renal outcome. This was especially the case for patients with either a focal or sclerotic-class renal biopsy, whereas the crescentic and mixed classes showed different results in the validation studies. These differences could be due to differences in patient populations or therapy, inter-rater reliability and lack of inclusion of tubulointerstitial lesions in the classification. Therapy is known to influence renal outcome, but due to the retrospective design of the to-date performed validation studies, this parameter could not be fully accounted for in these validation studies. Inter-rater reliability among three histopathologists was investigated in one study and was moderate.
Summary: The histopathological classification of ANCA-associated glomerulonephritis predicts renal outcome during follow-up, especially in patients with a focal or sclerotic-class renal biopsy. A large international validation study is currently being performed.
Video abstract: http://links.lww.com/CONH/A6.