title: The diagnosis of GI stromal tumors with EUS-guided fine needle aspiration with immunohistochemical analysis.
abstract: BACKGROUND
  With the advent of immunohistochemical analysis, the term "gastrointestinal stromal tumor" (GIST) was proposed to designate the largest category of primary nonepithelial neoplasms. EUS-guided fine needle aspiration (EUS-FNA) is useful for diagnosis of GISTs. The aim of this study was to evaluate the phenotyping of GISTs and diagnosis of malignant GISTs by using EUS-FNA with immunohistochemical analysis.
  
  
  METHODS
  A diagnosis of GIST was made in 23 patients by using EUS-FNA with immunohistochemical analysis. The accuracy of EUS-FNA diagnosis compared with the EUS imaging alone was analyzed. Additionally, immunophenotyping of specimens obtained by EUS-FNA and surgical resection specimens was compared. Factors that were diagnostic for malignant GISTs were also analyzed.
  
  
  RESULTS
  The overall accuracy for the diagnosis of malignant GIST was 78% (18/23) by EUS imaging alone and 91% (21/23) by histopathologic evaluation (H&E staining) of specimens obtained by EUS-FNA. In 21 of 23 cases (91%) the immunohistochemical expressions of c-kit, CD34, muscle actin, and S-100 coincided for the FNA and surgical specimens. The presence of mitotic cells (p = 0.011) and the Ki-67 labeling index (p < 0.0001) with respect to the FNA specimens were significant predictive factors for malignant GIST. For the diagnosis of malignant GIST, the accuracy, sensitivity, and specificity of EUS-FNA with the addition of Ki-67 immunohistochemical staining were 100%.
  
  
  CONCLUSIONS
  EUS-FNA with immunohistochemical analysis is useful in the preoperative diagnosis of GIST. It provides abundant information on immunohistochemical subtyping and on the capacity of the tumor for cellular progression.
authors.affiliation: Second Department of Internal Medicine, Nagoya University School of Medicine, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Ando
authors.forename: Hidemi
authors.initials: H
authors.lastname: Goto
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Niwa
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Hirooka
authors.forename: Naoki
authors.initials: N
authors.lastname: Ohmiya
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nagasaka
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hayakawa
mesh_terms: D000199:Actins / Q000032:analysis; D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis*; D001707:Biopsy, Needle; D019160:Endosonography; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008875:Middle Aged; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D012680:Sensitivity and Specificity; D018084:Ultrasonography, Interventional
chemical_list: D000199:Actins; D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D009418:S100 Proteins; D019009:Proto-Oncogene Proteins c-kit