title: Primary extragastrointestinal stromal tumors: a clinicopathological and immunohistochemical study - a tertiary care center experience.
abstract: BACKGROUND
  Extra gastrointestinal stromal tumors (EGIST) are uncommon compared to their gastrointestinal counterparts. EGISTs involve omentum, mesentery, retroperitoneum, pancreas, and pelvis.
  
  
  METHODS
  Ten EGISTs were analyzed in this study from January 1995 to November 2011. They were analyzed with respect to clinical features, imageological, histopathological, and immunohistochemical findings. The immunohistochemical stains used were Smooth muscle actin (SMA), Desmin, S-100 protein, CD34 and CD-117.
  
  
  RESULTS
  There was slight female preponderance with wide age range. Four of the tumors were in retroperitoneum, three in mesentery, and two in omentum and one in pelvis. Histopathologically majority were spindle cell tumors. Immunohistochemically CD117 was consistently positive followed by CD34. Smooth muscle actin was positive in eight cases, S-100 protein and desmin were positive in two cases each.
  
  
  CONCLUSIONS
  EGISTs are rare and should be considered in the differential diagnosis of the mesenchymal tumors and immunohistochemistry helps to confirm the diagnosis. Further study with better follow-up is desired to characterize these uncommon tumors.
authors.affiliation: Department of Pathology, Sri Venketeswar Institute of Medical Sciences, Tirupati, Andhra Pradesh 517 507, India.
authors.forename: R
authors.initials: R
authors.lastname: Patnayak
authors.forename: A
authors.initials: A
authors.lastname: Jena
authors.forename: S
authors.initials: S
authors.lastname: Parthasarathy
authors.forename: P D
authors.initials: PD
authors.lastname: Prasad
authors.forename: M K
authors.initials: MK
authors.lastname: Reddy
authors.forename: A K
authors.initials: AK
authors.lastname: Chowhan
authors.forename: N
authors.initials: N
authors.lastname: Rukamangadha
authors.forename: B V
authors.initials: BV
authors.lastname: Phaneendra
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging / Q000473:pathology; D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009372:Neoplasms, Connective Tissue / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D010534:Peritoneal Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D011860:Radiography, Abdominal; D011877:Radionuclide Imaging; D012509:Sarcoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D062606:Tertiary Care Centers; D055815:Young Adult
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D018952:Antigens, CD34; D019009:Proto-Oncogene Proteins c-kit