title: Histopathological Features of Gastrointestinal Stromal Tumors and the Contribution of DOG1 Expression to the Diagnosis.
abstract: BACKGROUND
  Gastrointestinal stromal tumors (GIST) have KIT or platelet-derived growth factor receptor α (PDGFRα) mutations affecting receptor tyrosine kinase activity and do not benefit from classic treatment regimens.
  
  
  OBJECTIVE
  The aim of this study was to review the algorithm that may be followed for the diagnosis and differential diagnosis in GISTs by investigating the histomorphological parameters and expression characteristics of classical immunohistochemical antibodies used in routine tests in addition to DOG1 expression.
  
  
  METHODS
  Diagnostic accuracy study.
  
  
  METHODS
  We reevaluated the histological and immunohistochemical parameters of 37 GISTs. The standard immunohistochemical diagnosis and differential diagnosis panel antibodies (CD117, PDGFRα, CD34, vimentin, desmin, SMA, S-100, and Ki67) were studied on the tumor sections. We also used the popular marker DOG1 antibody with accepted sensitivity for GISTs in recent years and the PDGFRα immune marker for which the benefit in routine practice is discussed.
  
  
  RESULTS
  Classification according to progressive disease risk groups of the 37 cases revealed that 54% were in the high risk, 19% in the moderate risk, 16% in the low risk, 8% in the very low risk and 8% in the no risk group. Cytological atypia, necrosis, mucosal invasion and the Ki67 index were found to be related to the progressive disease risk groups of the tumors (p<0.05). Positive immunoreaction was observed with CD117 and PDGFRα in all GISTs in the study (100%). Positivity with the DOG1 antibody was found in 33 (89%) cases. CD34 was positive in 62% (23) of the cases.
  
  
  CONCLUSIONS
  The CD117 antibody still plays a key role in GIST diagnosis. However, the use of DOG1 and PDGFRα antibodies combined with CD117 as sensitive markers can be beneficial.
authors.affiliation: Department of Pathology, Bezmialem Vakıf University Faculty of Medicine, İstanbul, Turkey.
authors.forename: Beril
authors.initials: B
authors.lastname: Güler
authors.affiliation: Department of Pathology, Trakya University Faculty of Medicine, Edirne, Turkey.
authors.forename: Filiz
authors.initials: F
authors.lastname: Özyılmaz
authors.affiliation: Department of Public Health, Trakya University Faculty of Medicine, Edirne, Turkey.
authors.forename: Burcu
authors.initials: B
authors.lastname: Tokuç
authors.affiliation: Department of Pathology, Trakya University Faculty of Medicine, Edirne, Turkey.
authors.forename: Nuray
authors.initials: N
authors.lastname: Can
authors.affiliation: Department of Pathology, Trakya University Faculty of Medicine, Edirne, Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Taştekin
keywords: CD117; DOG1; PDGFRα; gastrointestinal stromal tumors; histopathology; immunohistochemistry