A Case of Stage IV Gastric GIST in which Imatinib Therapy was Successful after Emergency Surgery for Perforated Peritonitis

A 72-year-old man visited our hospital with complaints of loss of appetite, abdominal pain, and weight loss. Physical examination revealed a painless mass in the upper left abdomen. A blood test revealed renal dysfunction and mild liver damage. Abdominal CT showed a mass lesion with a major axis of about 20 cm on the greater curvature side of the gastric corpus, a large number of soft shadows in the abdominal cavity, and a 30 mm-sized tumor in the liver S6. Upper gastrointestinal endoscopy revealed an ulcerative lesion deeper than UL III on the posterior wall of the curvatures of the middle body of the stomach. As a result of biopsy, immunohistochemical staining was positive for c-kit and weakly positive for CD34, so the diagnosis was gastric GIST. Since peritoneal dissemination and liver metastasis were observed, we judged that surgery was not indicated. On the 10th day of hospitalization, gastric perforation due to tumor self-destruction developed, so partial gastric resection including the main tumor was performed by emergency surgery. After the operation, administration of imatinib was started. CT examination 6 months after the operation revealed dissemination and liver metastasis almost disappeared. Disease control is maintained 12 months after surgery.