Atypical presentation of a gastric stromal tumor masquerading as a giant intraabdominal cyst: A case report.

Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms that arise in the gastrointestinal tract, accounting for ~1% of gastric malignancies. The present study reports the case of a GIST of the stomach in a 75-year-old man who presented with abdominal distension and anorexia for 1 month. Gastroscopy was unremarkable. Ultrasound and computed tomography (CT) scans showed a giant intraabdominal cystic lesion of unknown origin. The lesion was initially believed to be a duplication cyst, a pancreatic pseudocyst or a liver cyst in the pre-operative diagnosis. Exploratory laparotomy revealed a cystic lesion of the lesser sac originating from the lesser curvature of the stomach. A distal gastrectomy with en bloc resection of the lesion was performed. The intraoperative frozen section showed a spindle-cell GIST and microscopically negative margins. The patient was treated with imatinib for 1 year. The latest CT scan at 14 months post-surgery did not show any recurrence. Although GISTs presenting as predominantly cystic lesions are very rare, they should be considered in the differential diagnosis of cystic lesions of the upper abdomen.