title: Pathological diagnosis of antibody-mediated rejection in renal allograft without c4d staining, how much reliable?
abstract: BACKGROUND
  C4d as a part of complement activation process is a marker for detecting antibody-mediated rejection (ABMR) and its positivity accompanied by positive donor specific antibody (DSA), and morphologic view of humoral rejection has been suggested to detect ABMR since 2003.
  
  
  METHODS
  41 specimens of transplanted kidney biopsies gathered from 2006 to 2008 were evaluated for morphological changes on light microscopy, and nephro-pathologist made distinct diagnosis for all of specimens then c4d staining was done for all of them. The association between primary diagnosis without c4d staining and c4d scoring on peritubular capillaries and glomerular capillaries were evaluated to determine whether morphological changes were enough for distinct diagnosis or not.
  
  
  RESULTS
  Acute tubular necrosis (ATN) 27%, interstitial fibrosis and tubular atrophy (IF&TA) 17%, and T cell mediated rejection (TCMR) 22% were the commonest diagnosis on light microscopy, and 17% of all biopsies had diffuse positive c4d staining. There was not any report of ABMR in morphological evaluation while c4d positive staining was seen in some specimens (17%). It may result from masking of ABMR by other morphological changes such as TCMR and no specific histologic changes for ABMR on light microscopy.
  
  
  CONCLUSIONS
  We would like to emphasize that c4d staining should be done for all of renal allograft biopsies, and pathologists all over the world should consider the probability of ABMR masked by other morphological changes on light microscopic evaluation.
authors: Isfahan Kidney Diseases Research Center, Department of Pathology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Diana
authors: D
authors: Taheri
authors: Ardeshir
authors: A
authors: Talebi
authors: Maryam
authors: M
authors: Taghaodi
authors: Mehdi
authors: M
authors: Fesharakizadeh
authors: Mojgan
authors: M
authors: Mortazavi
authors: Afshin
authors: A
authors: Azhir
authors: Shahaboddin
authors: S
authors: Dolatkhah
authors: Noushin A
authors: NA
authors: Moghaddam
authors: Mohsen
authors: M
authors: Nasr
keywords: Antibody-mediated rejection; c4d; kidney transplantation