A case of gastrointestinal stromal tumor of the duodenum with a huge abscess

A 36-year-old man admitted for upper abdominal pain and fever. Enhanced abdominal computed tomography showed a cystic tumor with an air fluid level, measuring 140mm in size, along the side of the first and second portions of the duodenum. The common bile duct, portal vein, and proper hepatic artery were displaced by the tumor. Upper gastrointestinal endoscopy showed duodenal ulcer, but fistula was not confirmed. Combining all imaging and clinical findings, it was clinically diagnosed as duodenal submucosal tumor with abscess, and elective surgery was performed. There was a huge mass in the Morrison pouch, with severe adhesion to the second portion of the duodenum, gall bladder, common bile duct, and transverse colon. Subtotal stomach-preserving pancreaticoduodenectomy with transverse colectomy was performed. A fistula from the second portion of the duodenum to the tumor was confirmed on the resected specimen. Histological examination showed gastrointestinal stromal tumor originating in the duodenum.