title: A gastrointestinal stromal tumor with mesenteric and retroperitoneal invasion.
abstract: BACKGROUND
  Gastrointestinal stromal tumors are rare visceral sarcomas arising in the gastrointestinal tract wall. In this report we present a case of gastrointestinal stromal tumors with mesenteric and retroperitoneal invasion, describe and discuss its computed tomography findings.
  
  
  METHODS
  A 57-years-old male patient has been complaining of abdominal distention, weight lose, and hematuria. During physical examination, significant distention and multiple palpable tumor masses were identified on the abdomen. Abdominal computed tomography showed multiple, well-defined, soft tissue masses with homogenous and heterogeneous pattern, in the mesenteric and retroperitoneal areas. Unlike specific features of gastrointestinal stromal tumor, renal obstruction and atypical central calcification without chemotherapy that has not been yet described were seen in this case. Computed tomography did not reveal liver metastases and/or the lymph nodes with pathological size. Ultrasonography-guided true-cut biopsy was made, histopathologic and immunohistochemical analyses demonstrated stromal tumor which, C-KIT (+). The patient underwent left ureterectomy, left nephrectomy and total colectomy. Postoperative histopathological analyses revealed lower grade malignant GISTs. As of 17 months after the surgery, he is alive and free of recurrence.
  
  
  CONCLUSIONS
  When intraabdominal, multiple, large (>5 cm), well-circumscribed, homogenous or heterogeneous mass lesions without ascites, omental caking and lymph nodes metastases were seen, gastrointestinal stromal tumors should be considered in the differential diagnosis.
authors.affiliation: Department of Radiology, Istanbul University, Istanbul Faculty of Medicine, Istanbul, Turkey. gengin@istanbul.edu.tr
authors.forename: Gulgun
authors.initials: G
authors.lastname: Engin
authors.forename: Oktar
authors.initials: O
authors.lastname: Asoglu
authors.forename: Yersu
authors.initials: Y
authors.lastname: Kapran
authors.forename: Gulsen
authors.initials: G
authors.lastname: Mert
mesh_terms: D015746:Abdominal Pain / Q000175:diagnosis / Q000209:etiology; D001707:Biopsy, Needle; D005500:Follow-Up Studies; D046152:Gastrointestinal Stromal Tumors / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D007813:Laparotomy; D008297:Male; D008643:Mesentery; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology*; D009367:Neoplasm Staging; D010534:Peritoneal Neoplasms / Q000473:pathology* / Q000601:surgery; D012186:Retroperitoneal Neoplasms / Q000473:pathology* / Q000601:surgery; D018570:Risk Assessment; D016896:Treatment Outcome