title: Revision of gastrointestinal mesenchymal tumours with CD117.
abstract: BACKGROUND
  Tyrosinekinase inhibitors improve the treatment of gastrointestinal stromal tumours (GISTs) and their diagnosis has been facilitated by recently developed immunohistochemical markers. It is hypothesised that in the past, the true incidence of GISTs has been underestimated.
  
  
  OBJECTIVE
  To study the clinicopathological features of previously resected mesenchymal tumours of the gastrointestinal tract and determine the accuracy of previous diagnostic results.
  
  
  METHODS
  Patients with mesenchymal tumours of the gastrointestinal tract operated on between 1987 and 2002 were identified using medical and pathologic files. Immunohistochemical staining for CD117, CD34, desmin and S100 was performed, and diagnosis reviewed.
  
  
  RESULTS
  Thirty-six mesenchymal tumours were reanalysed. Before revision, diagnosis of GIST was correctly made in only six cases. Supportive use of immunohistochemical markers for accurate diagnosis of the remaining 30 previously undefined mesenchymal tumours yielded 17 additional GISTs. Therefore, 23 of 36 (63%) gastrointestinal mesenchymal tumours were shown to be GISTs.
  
  
  CONCLUSIONS
  The true incidence of GISTs has been underestimated. There is merit in reviewing the clinical diagnoses of all mesenchymal tumours of the gastrointestinal tract with modern immunohistochemical markers. This may enhance clinical decision making.
authors.affiliation: Department of Surgery, Medisch Centrum Rijnmond-Zuid locatie Clara, Olympiaweg 350, 3078 HT Rotterdam, The Netherlands.
authors.forename: J P
authors.initials: JP
authors.lastname: de Schipper
authors.forename: R S L
authors.initials: RS
authors.lastname: Liem
authors.forename: H F G M
authors.initials: HF
authors.lastname: van den Ingh
authors.forename: E
authors.initials: E
authors.lastname: van der Harst
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism*; D003893:Desmin / Q000378:metabolism; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000378:metabolism* / Q000601:surgery*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D012086:Reoperation; D012189:Retrospective Studies; D009418:S100 Proteins / Q000378:metabolism
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D003893:Desmin; D009418:S100 Proteins; D019009:Proto-Oncogene Proteins c-kit