title: C-kit overexpression is not associated with KIT gene mutations in chromophobe renal cell carcinoma or renal oncocytoma.
abstract: BACKGROUND
  C-kit overexpression has previously been described in chromophobe renal cell carcinoma (cpRCC) and renal oncocytoma (RO). However, so far no KIT mutations have been found. The objective of our study was to analyse c-kit in a large cohort of renal tumors and to perform KIT mutation analysis in a subset cpRCC and RO cases with overexpression of c-kit.
  
  
  METHODS
  We studied the immunohistochemical expression of c-kit on tissue microarrays containing formalin-fixed, paraffin-embedded samples of 948 patients with renal tumors. CpRCC and RO cases with c-kit overexpression (n=23) were analyzed for KIT mutations in exons 9, 11, 13, 14, 15, and 17.
  
  
  RESULTS
  Expression of c-kit was found in 6/642 (0.9%) clear cell RCC, 3/154 (1.9%) papillary RCC, 54/69 (78.3%) cpRCC, 37/45 (82.2%) RO and 2/30 (6.7%) of other unclassified tumor types. In none of the RO and cpRCC cases analyzed, a KIT gene mutation was found.
  
  
  CONCLUSIONS
  C-kit expression is found in the majority of cpRCC and RO, but these tumors do not harbor the usual c-kit activating mutations. This may have implications for the use of tyrosine kinase inhibitors in patients with advanced cpRCC and c-kit expression.
authors.affiliation: Institute of Pathology, University of Rostock, Strempelstr. 14, 18055 Rostock, Germany. Electronic address: annette.zimpfer@med.uni-rostock.de.
authors.forename: Annette
authors.initials: A
authors.lastname: Zimpfer
authors.affiliation: Institute of Pathology, University of Rostock, Strempelstr. 14, 18055 Rostock, Germany; Department of Urology, University of Rostock, Ernst-Heydemann-Str. 8, 18057 Rostock, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Janke
authors.affiliation: Institute of Pathology, University of Rostock, Strempelstr. 14, 18055 Rostock, Germany.
authors.forename: Maja
authors.initials: M
authors.lastname: Hühns
authors.affiliation: Institute of Pathology, University of Rostock, Strempelstr. 14, 18055 Rostock, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Schneider
authors.affiliation: Institute for Biostatistics and Informatics in Medicine, University of Rostock, Ernst-Heydemann-Str. 8, 18057 Rostock, Germany.
authors.forename: Günther
authors.initials: G
authors.lastname: Kundt
authors.affiliation: Rostock Cancer Registry, University of Rostock, Südring 75, 18059 Rostock, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Zettl
authors.affiliation: Institute of Pathology, Charité University Medicine, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Ergin
authors.initials: E
authors.lastname: Kilic
authors.affiliation: Department of Urology, University of Rostock, Ernst-Heydemann-Str. 8, 18057 Rostock, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Maruschke
authors.affiliation: Department of Urology, University of Rostock, Ernst-Heydemann-Str. 8, 18057 Rostock, Germany.
authors.forename: Oliver W
authors.initials: OW
authors.lastname: Hakenberg
authors.affiliation: Institute of Pathology, University of Rostock, Strempelstr. 14, 18055 Rostock, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Erbersdobler
mesh_terms: D018249:Adenoma, Oxyphilic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism*; D055815:Young Adult
chemical_list: D019009:Proto-Oncogene Proteins c-kit
keywords: C-kit; Chromophobe renal cell carcinoma; KIT gene mutation; Renal oncocytoma