A Case of Adenocarcinoma Arising in Heterotopic Pancreas with Gastrointestinal Bleeding

A 75-year-old man was admitted to our hospital with melena. He was diagnosed as having an arterial hemorrhage of a submucosal tumor on the antimesenteric side of the second portion of the duodenum. Due to difficulties with endoscopic hemostasis and arterial embolization, we performed emergency partial resection of the duodenum. Examination of frozen sections confirmed that the tumor was a well differentiated adenocarcinoma arising from the heterotopic ductal structure. In addition, pancreaticoduodenectomy with preservation of the pylorus was performed. Immunohistochemical studies confirmed that the tumor was an adenocarcinoma arising from a heterotopic pancreas, which is extremely rare and makes an exact preoperative diagnosis difficult. We suggest that examination of frozen operative sections should be performed in confirming whether the heterotopic pancreas is benign or malignant and, in the case of a malignant lesion, extensive resection is required.