Adenocarcinoma arising from heterotopic pancreas at the first portion of the duodenum: a case report.

Malignant transformation of a heterotopic pancreas in the duodenum is very rare. To our knowledge, only 15 cases have been reported worldwide, including the present case. We herein report a rare case of malignant transformation of a heterotopic pancreas in the duodenum along with a review of the literature.A 65-year-old man was admitted to our hospital for evaluation of dyspepsia and vomiting. Esophagogastroduodenoscopy showed a stricture of the duodenal bulb. Laparoscopic distal gastrectomy was performed. Although a duodenal tumor had not been suspected, histopathological examination of the surgical specimen showed adenocarcinoma arising from a heterotopic pancreas (Heinrich type III) in the duodenum. Four months postoperatively, the patient received adjuvant chemotherapy. He was still alive without recurrence at 24 months of follow-up.Adenocarcinoma arising in a heterotopic pancreas is rare; therefore, preoperative diagnosis is difficult to obtain. Effective management of a heterotopic pancreas depends on the presence or absence of symptoms. Awareness of the possibility of malignant change in a heterotopic pancreas of the duodenum prior to surgery is helpful for the diagnosis and appropriate management of such patients.