A Duodenal Gastrointestinal Stromal Tumor with Extrahepatic Portal Vein Aneurysm that was Difficult to Diagnose from a Pancreatic Tumor—A Case Report—

Abstract

A 55-year-old woman was referred to our hospital because a physical check-up suggested that she might have gallbladder polyps. Abdominal computed tomography (CT) showed a pancreatic mass and extrahepatic portal vein aneurysm. CT and magnetic resonance imaging revealed a 30-mm cystic mass with a solid component and wall calcification in the head of the pancreas. A 29-mm portal vein aneurysm located near the junction of the superior mesenteric vein and splenic vein. Endoscopic ultrasonography also revealed a 30-mm hypoechoic mass located in the uncinate process and just below the papilla of Vater and calcifications present partially within and outside the mass.

Fine-needle aspiration was performed, but there was no definitive diagnosis. Pylorus-preserving pancreaticoduodenectomy was performed because the imaging findings raised the suspicion of a solid pseudopapillary neoplasm or pancreatic neuroectodermal tumor. Portal vein aneurysm resection was not performed because a tendency toward an increase in aneurysm size was not observed. Postoperative pathological diagnosis was based on the mass, which reached the proper muscle layer of the duodenum. The mass, which tested positive for c-kit, was represented by bundles and tangled structures of spindle-shaped cells, leading to a final diagnosis of a duodenal gastrointestinal stromal tumor.