title: Fine needle aspiration of gastrointestinal stromal tumors.
abstract: OBJECTIVE
  Gastrointestinal stromal tumors (GISTs) are uncommon mesenchymal tumors of the gastrointestinal tract. Fine needle aspiration (FNA) is one option for diagnosing GISTs before surgery. This study was designed to evaluate the clinical utility of FNA in the diagnosis of GISTs.
  
  
  METHODS
  FNAs from 19 GISTs originating in the stomach, small bowel and colon obtained from 1988 to 1998 were studied. Immunocytochemistry was performed on 12 cases. The GISTs were classified as benign, borderline and malignant, according to location, size, mitotic activity and clinical outcome.
  
  
  RESULTS
  Benign (three) and borderline (five) GISTs were all spindle cell type; malignant GISTs included five spindle cell type and six epithelioid type. Most smears contained abundant cellular material. Benign and borderline GISTs of spindle cell type tended to have cells arranged in tightly cohesive clusters, while malignant GISTs were more likely to exhibit loosely cohesive groups with many single cells, occasional nuclear pleomorphism, hyperchromasia and irregular nuclear contours. Epithelioid-type GISTs mimicked adenocarcinoma. Mitoses were seldom observed in either type. CD117 (KIT protein product) was demonstrated by immunocytochemistry in 9 cases, CD34 in 11, desmin in 3, S-100 protein in 2 and smooth muscle actin in 6 cases.
  
  
  CONCLUSIONS
  FNA can be used to diagnose GISTs as spindle cell and epithelioid types, but cytomorphology alone cannot be used to assess malignant potential. Immunocytochemical staining for CD117 is helpful in confirming the diagnosis. Care must be taken to differentiate epithelioid-type GISTs from adenocarcinoma.
authors.affiliation: Department of Pathology, Columbia University College of Physicians and Surgeons, VC 14-215, 630 West 168th Street, New York, New York 10032, USA. sl828@columbia.edu
authors.forename: S Q
authors.initials: SQ
authors.lastname: Li
authors.forename: T J
authors.initials: TJ
authors.lastname: O'Leary
authors.forename: S B
authors.initials: SB
authors.lastname: Buchner
authors.forename: R M
authors.initials: RM
authors.lastname: Przygodzki
authors.forename: L H
authors.initials: LH
authors.lastname: Sobin
authors.forename: Y S
authors.initials: YS
authors.lastname: Erozan
authors.forename: D L
authors.initials: DL
authors.lastname: Rosenthal
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis; D000368:Aged; D018952:Antigens, CD34 / Q000032:analysis / Q000276:immunology; D014408:Biomarkers, Tumor / Q000032:analysis / Q000276:immunology; D001707:Biopsy, Needle; D003937:Diagnosis, Differential; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000145:classification / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009372:Neoplasms, Connective Tissue / Q000145:classification / Q000175:diagnosis / Q000473:pathology*; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis / Q000276:immunology; D012189:Retrospective Studies
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D019009:Proto-Oncogene Proteins c-kit