Extra-Gastrointestinal Stromal Tumor of the Greater Omentum: Unusual Case Report

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract, originating from the interstitial cells of Cajal and most frequently expressing CD-117, a C-kit proto-oncogene, which can be detected immunohistochemically. Extra-gastrointestinal stromal tumors are neoplasms with similar immunohistological features arising outside the gastrointestinal tract with no connection to the gastric or intestinal wall.We report the case of a 61-year-old Moroccan man who presented with chronic abdominal pain along with progressive abdominal distension for the past last year. The clinical examination demonstrated a large abdominal mass and an abdominal computed tomography scan revealed a voluminous intraperitoneal mass measuring 30 cm in its greatest diameter. At laparotomy, this mass seemed to be arising from the greater omentum without continuity to the gastrointestinal tract. The mass was completely removed with clear margins and pathological examination was suggestive for high-risk gastrointestinal stromal tumor of the greater omentum. Due to the aggressive nature of this patient's tumor, he was assigned to receive imatinib as adjuvant chemotherapy for 3 years. He remains alive without any sign of recurrence after 4 years of follow-up.Extra-gastrointestinal stromal tumors of the greater omentum can grow slowly and remain clinically silent despite the large size of the tumor. Complete surgical resection is the only effective treatment approach. Nevertheless, adjuvant therapy following resection with imatinib has become a standard of care in cases of high risk disease.