title: Analysis of CD117-negative gastrointestinal stromal tumors.
abstract: OBJECTIVE
  To identify the gastrointestinal stromal tumors (GISTs) that are negative for CD117 expression by immunohistochemistry and to characterize their malignant potential.
  
  
  METHODS
  A total of 108 primary mesenchymal tumors of the gastrointestinal tract were screened to select CD117-negative tumors, from which KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 10, 12, 14, and 18) were sequenced to identify GISTs. Tumor recurrence and distant metastasis were used as the criteria of malignancy.
  
  
  RESULTS
  The result showed that approximately 25% (29/108) of the gastrointestinal mesenchymal tumors were negative for CD117 and approximately 6% (7/108) of the tumors were CD117-negative GISTs. All these CD117-negative tumors had a mutated KIT and a wild-type PDGFRA. All CD117-negative GISTs with mutations at codons 557/558 of KIT had mitotic counts >10/50 high power field, and 75% (3/4) of them showed multiple recurrence or distant metastasis.
  
  
  CONCLUSIONS
  CD117-negative KIT mutated GISTs account for approximately 6% of the gastrointestinal mesenchymal tumors. Tumor recurrence or distant metastasis correlates to both the KIT mutations at codons 557/558 and the mitotic counts, but not to the tumor size.
authors.affiliation: Department of Pathology, Mackay Memorial Hospital, 45, Minsheng Road, Tamshui, Taipei, Taiwan, China. jeffrey@ms2.mmh.org.tw
authors.forename: Chin-Yuan
authors.initials: CY
authors.lastname: Tzen
authors.forename: Bey-Liing
authors.initials: BL
authors.lastname: Mau
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D014408:Biomarkers, Tumor; D005091:Exons; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000378:metabolism* / Q000503:physiopathology / Q000556:secondary*; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D009364:Neoplasm Recurrence, Local; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; D019009:Proto-Oncogene Proteins c-kit; D017479:Receptors, Platelet-Derived Growth Factor
references.citation: Am J Surg Pathol. 1983 Sep;7(6):507-19
references.pmid: 6625048
references.citation: Science. 2003 Jan 31;299(5607):708-10
references.pmid: 12522257
references.citation: Hum Pathol. 2002 May;33(5):459-65
references.pmid: 12094370
references.citation: J Clin Oncol. 2002 Sep 15;20(18):3898-905
references.pmid: 12228211
references.citation: Am J Pathol. 1998 May;152(5):1259-69
references.pmid: 9588894
references.citation: Hum Pathol. 2002 May;33(5):484-95
references.pmid: 12094373
references.citation: Am J Pathol. 2000 Oct;157(4):1091-5
references.pmid: 11021812
references.citation: Am J Surg Pathol. 2003 May;27(5):625-41
references.pmid: 12717247
references.citation: Lab Invest. 1998 Dec;78(12):1633-6
references.pmid: 9881963
references.citation: Hum Pathol. 1984 Mar;15(3):229-32
references.pmid: 6421716
references.citation: J Pathol. 2001 Apr;193(4):505-10
references.pmid: 11276010
references.citation: Cancer Res. 2001 Nov 15;61(22):8118-21
references.pmid: 11719439
references.citation: Am J Pathol. 1999 Jan;154(1):53-60
references.pmid: 9916918