title: Extracapillary proliferation in IgA nephropathy; recent findings and new ideas.
abstract: BACKGROUND
  IgA nephropathy (IgAN) is an autoimmune disorder and is the most common form of primary glomerulonephritis (GN) worldwide.
  
  
  METHODS
  Directory of Open Access Journals (DOAJ), Google Scholar, PubMed (NLM), LISTA (EBSCO) and Web of Science have been searched.
  
  
  RESULTS
  It is a slowly progressing disorder that leads to end-stage renal disease (ESRD) in up to 50% of the patients within 25 years of the onset of the disease. IgAN is defined by predominant IgA deposition in the mesangial area on immunofluorescence (IF) microscopy. Its histology varies from mild focal segmental proliferation of mesangial cells to severe diffuse global proliferation with extracapillary proliferation (crescent formation). The Oxford classification, designed in 2009, is a new classification for the evaluation of morphologic lesions of IgAN. This classification, containing four pathology variables, was found to have prognostic implications. The variables included are mesangial hypercellularity (M), endocapillary proliferation (E), segmental glomerulosclerosis (S) and the proportion of interstitial fibrosis and tubular atrophy (T). However, crescents were not included in the Oxford classification.
  
  
  CONCLUSIONS
  In this mini-review, we describe the recent publications about the significance of extracapillary proliferation in IgAN and we conclude that, there is much controversy about the role of extracapillary proliferation as a significant prognostic factor in IgAN. Hence, it is important to re-consider crescents in IgAN patients. Therefore, we suggest further investigations on this aspect of IgAN disease.
authors: Department of Nephrology, Division of Nephropathology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Hamid
authors: H
authors: Nasri
authors: Department of Histopathology, Sindh Institute of Urology and Transplantation (SIUT), Karachi, Pakistan.
authors: Muhammed
authors: M
authors: Mubarak
keywords: Crescents; End-stage renal disease; Extracapillary proliferation; IgA nephropathy; Oxford classification