Background: Although heterotopic pancreas in the gastrointestinal tract is not uncommon, jejunal pancreatic heterotopia is a rare finding, and malignant transformation in such a location is very unusual.
Methods: We encountered a case of jejunal carcinoma in pancreatic heterotopia and because of its rarity, we reviewed the Armed Forces Institute of Pathology experience as well as the literature. The clinical, histopathologic, and immunohistochemical features were studied.
Results: In 109 patients diagnosed as having pancreatic heterotopia in the gastrointestinal tract between 1970 and 1997 at the Armed Forces Institute of Pathology, 67 cases (62%) occurred in the stomach, 42 (38%) in the small intestine, and none in the large intestine. We found 2 patients with adenocarcinoma arising in pancreatic heterotopia. The 2 cases arose in the jejunum. One was of the ductal type, while the other was an acinar cell carcinoma with focal ductular differentiation. In both cases the nontumoral pancreatic tissue contained ducts, acini, and islets. Review of the literature yielded 26 reports of 28 cases of carcinoma arising in heterotopic pancreas; of these, 18 were well documented. Only 1 occurred in the jejunum, and none was of the acinar type.
Conclusions: Carcinoma in pancreatic heterotopia is rare, and acinar cell carcinoma in pancreatic heterotopia is extremely rare. Recognition of carcinoma in pancreatic heterotopia is important to prevent its misinterpretation as a metastatic tumor.