Giant cyst-containing gastrointestinal stromal tumor of the stomach, which developed outside the gastric wall—a case report—

Abstract

An 67-year-old man was visited a hospital because of back pain over a 1-year period. Abdominal CT revealed a giant abdominal tumor, and he was referred to our hospital. Abdominal CT and MRI performed at our hospital showed a giant 18×10 cm-diameter polycystic tumor that was compressing the liver, gall bladder, colon, duodenum, stomach, and pancreas. The tumor was heterogeneously enhanced inside and was found to have a solid part that was attached to the stomach. Upper gastrointestinal endoscopy showed a normal mucosal surface, and abdominal angiography indicated the right gastroepiploic artery as the feeding artery. These findings suggested that the tumor was a gastrointestinal stromal tumor (GIST) or malignant fibrous histiocytoma (MFH) that originated in the stomach or omentum ; but no definitive diagnosis could be made. Because the tumor was attached to the anterior wall of the stomach, tumor resection was performed together with a partial gastrectomy. The resected specimen was 22×13×10 cm in size and weighed 965 g. Histopathological testing revealed the presence of both spindle cells and round cells in the specimen. Immunohistochemical analysis showed that the specimen was positive for c-kit and CD34, and the patient was coclusively diagnosed as having GIST of the stomach. Cases of GIST with giant cyst formation are occasionally reported, but GISTs of the stomach that are more than 20 cm in diameter seem to be rare ; therefore, we have reported this case, together with some bibliographical information.