title: CD 9 and vimentin distinguish clear cell from chromophobe renal cell carcinoma.
abstract: BACKGROUND
  Clear cell renal cell carcinoma (ccRCC) and chromophobe renal cell carcinoma (chRCC) can usually be distinguished by histologic characteristics. Occasionally, diagnosis proves challenging and diagnostic difficulty will likely increase as needle biopsies of renal lesions become more common.
  
  
  METHODS
  To identify markers that aid in differentiating ccRCC from chRCC, we used gene expression profiles to identify candidate markers that correlate with histology. 39 antisera and antibodies, including 35 for transcripts identified from gene expression profiling, were evaluated. Promising markers were tested on a tissue microarray (TMA) containing 428 renal neoplasms. Strength of staining of each core on the TMA was formally scored and the distribution of staining across different types of renal neoplasms was analyzed.
  
  
  RESULTS
  Based on results from initial immunohistochemical staining of multitissue titer arrays, 23 of the antisera and antibodies were selected for staining of the TMA. For 7 of these markers, strength of staining of each core on the TMA was formally scored. Vimentin (positive in ccRCC) and CD9 (positive in chRCC) best distinguished ccRCC from chRCC. The combination of vimentin negativity and CD9 positivity was found to distinguish chRCC from ccRCC with a sensitivity of 100.0% and a specificity of 95.2%.
  
  
  CONCLUSIONS
  Based on gene expression analysis, we identify CD9 and vimentin as candidate markers for distinguishing between ccRCC and chRCC. In difficult cases and particularly when the amount of diagnostic tissue is limited, vimentin and CD9 staining could serve as a useful adjunct in the differential diagnosis of ccRCC and chRCC.
authors.affiliation: Department of Urology, Stanford University, California, USA. aaw7@stanford.edu
authors.forename: Ariel A
authors.initials: AA
authors.lastname: Williams
authors.forename: John P T
authors.initials: JP
authors.lastname: Higgins
authors.forename: Hongjuan
authors.initials: H
authors.lastname: Zhao
authors.forename: Börje
authors.initials: B
authors.lastname: Ljunberg
authors.forename: James D
authors.initials: JD
authors.lastname: Brooks