[A case of a giant gastrointestinal stromal tumor of the stomach with extramural growth].

The patient was a 58-year-old man who visited our hospital with a chief complaint of rapidly aggravating feeling of epigastric distension and gastralgia. A giant mass, with a major axis of 22 cm, excluding the upper abdominal organs such as the stomach, liver, and pancreas and containing cystic and solid components was observed on abdominal computed tomography( CT). Laparotomy was performed with the aim of differentiating between a gastrointestinal stromal tumor (GIST) arising from the stomach or omentum and abdominal soft tissue tumors. The mass was a giant tumor accompanied by cystic and solid components that had developed extramurally from the stomach wall and strongly adhered to the left hepatic lobe and diaphragm, for which total gastrectomy, Roux-en-Y reconstruction, partial hepatectomy, and combined resection of the diaphragm were performed. Histopathologically, overgrowth of spindle cells in a disarrayed arrangement was noted, and immunostaining was positive for c-kit and CD 34. On the basis of these findings, the patient was diagnosed as having gastric GIST. Imatinib administration was initiated soon after surgery. There was no evidence of recurrence or metastasis for about 1 year after the surgery. We encountered a patient with a giant cystic GIST of the stomach that was larger than 20 cm and that could surgically resected.