title: Utility of cytokeratin 7 for distinguishing chromophobe renal cell carcinoma from renal oncocytoma.
abstract: OBJECTIVE
  Chromophobe renal cell carcinoma is a relatively uncommon variant of renal carcinoma described in 1985. The main differential diagnosis is renal oncocytoma. Hale's colloidal iron staining is a powerful adjunct to morphological interpretation but it is not specific and is sometimes difficult to interpret. We studied the immunohistochemical expression of cytokeratin 7 to determine its value in distinguishing chromophobe renal cell carcinoma from renal oncocytoma.
  
  
  METHODS
  Immunostaining was performed on paraffin-embedded tumor tissue of 6 chromophobe renal cell carcinomas and 11 oncocytomas with an antibody to cytokeratin 7 (clone OV-TL 12/30, Dako, France) using a streptavidin-biotin method.
  
  
  RESULTS
  All chromophobe renal cell carcinomas showed strong cytoplasmic staining with peripheral cell accentuation. In contrast, 8 of 11 oncocytomas were entirely negative and 3 showed only weak and focal staining in less than 5% of the tumor cells.
  
  
  CONCLUSIONS
  Immunohistochemical staining for cytokeratin 7 may be useful for the differential diagnosis of renal oncocytomas and chromophobe renal cell carcinomas when Hale's colloidal iron staining is uncertain.
authors.affiliation: Department of Pathology, CHRU, Lille, France. bgosselin@chru-lille.fr
authors.forename: X
authors.initials: X
authors.lastname: Leroy
authors.forename: D
authors.initials: D
authors.lastname: Moukassa
authors.forename: M C
authors.initials: MC
authors.lastname: Copin
authors.forename: F
authors.initials: F
authors.lastname: Saint
authors.forename: E
authors.initials: E
authors.lastname: Mazeman
authors.forename: B
authors.initials: B
authors.lastname: Gosselin
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery; D018249:Adenoma, Oxyphilic / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D053552:Keratin-7; D007633:Keratins; D007680:Kidney Neoplasms / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: C507497:KRT7 protein, human; D053552:Keratin-7; D007633:Keratins