[A case of ruptured gastrointestinal stromal tumor of the duodenum with intraabdominal bleeding].

We report a case of ruptured gastrointestinal stromal tumor (GIST) of the duodenum with intraabdominal bleeding. A 50-year-old man was admitted to our hospital because of sudden epigastralgia. Enhanced computed tomography (CT) showed a tumor measuring about 14 cm in diameter on the ventral side of the right kidney and intrapelvic fluid collection. We performed an emergency operation. At laparotomy, the tumor was originated from the 2nd portion of the duodenum without attaching to the retroperitoneum. We resected the tumor radically. Histopathologically, the tumor arose from the proper muscle layer of the duodenum, and was positive for c-kit and negative for CD34 and α-SMA on immunostaining. Then the tumor was diagnosed as GIST of the duodenum. Adjuvant therapy by imatinib 400 mg/day is now being done because this case is thought to be clinically malignant GIST.