title: Gastrointestinal stromal tumors: a clinicopathological and immunohistochemical study of 121 cases.
abstract: BACKGROUND
  Primary mesenchymal tumors of the gastrointestinal tract are a heterogeneous group of tumors with a wide clinical spectrum, of which gastrointestinal stromal tumors (GIST) typically occur in middle-aged to older individuals. This study evaluated the clinicopathological and morphological features of GIST of the intestinal tract.
  
  
  METHODS
  The study included 108 gastrointestinal and 13 extra-gastrointestinal stromal tumors involving the mesentry and retroperitoneum between January 1989 and July 2007. Immunohistochemical expression of CD117, CD34, SMA, Desmin, S100, and Ki-67 were studied.
  
  
  RESULTS
  GIST comprised 108 of 120 (90%) of the mesenchymal tumors. The tumor was located in the stomach in the majority (55%) of patients followed by small intestine (30%), retroperitoneum (7%) and the colorectum (4%). There was a significant correlation between tumor size and mitotic index, with larger tumors having higher mitotic index (p < 0.001). Mitotic index per 5 mm(2) correlated with high cellularity (p < 0.001), presence of necrosis (p < 0.001) and presence of mucosal invasion (p = 0.01). Expression of CD117 was seen in 94%, CD34 in 59%, SMA in 41%, S-100 in 33%, and desmin in 4% of tumors.
  
  
  CONCLUSIONS
  We found GIST to be the most common mesenchymal tumor of the gastrointestinal tract.
authors.affiliation: Department of Pathology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226 014, Uttar Pradesh, India.
authors.forename: Mukul
authors.initials: M
authors.lastname: Vij
authors.forename: Vinita
authors.initials: V
authors.lastname: Agrawal
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
authors.forename: Rakesh
authors.initials: R
authors.lastname: Pandey
mesh_terms: D000199:Actins / Q000032:analysis; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis*; D003893:Desmin / Q000032:analysis; D046152:Gastrointestinal Stromal Tumors / Q000145:classification / Q000175:diagnosis* / Q000473:pathology*; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008875:Middle Aged; D008940:Mitotic Index; D009336:Necrosis; D009361:Neoplasm Invasiveness; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D055815:Young Adult
chemical_list: D000199:Actins; D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D003893:Desmin; D019394:Ki-67 Antigen; D019009:Proto-Oncogene Proteins c-kit; D009418:S100 Proteins; C498862:Acta2 protein, rat