Background: Circumportal pancreas or portal annular pancreas, is a rare congenital fusion anomaly of the dorsal and ventral pancreas in which the pancreatic tissue encases the portal and/or superior mesenteric vein. The prevalence of this rare and overlooked anomaly is 1.4 to 2.5% on multidetector computed tomography series. Altough it is usually asymptomatic and incidentally detected, it can complicate cancer diagnosis and surgery of the periampullary region. On the diagnostic side it might look like tumor extension around major vessels imitating locally advanced cancer. On the surgical side, it necessitates complete resection of the posterior portion, complicating the surgery and likely increasing the fistula rate. Methods: Herein, we present a case of ampullary cancer accompanied by by circumportal pancreas, preoperatively diagnosed on radiological examination using ceCT and MRI and confirmed by intraoperative pancreaticography during surgical resection. A pylorus preserving Whipple operation was performed with resection of the aberrant portion of the pancreas. The merging of the anomalous duct was identified and sewn on the inferior portion of the pancreas. Results: Pathologic analysis of the specimen confirmed the diagnosis of circumportal pancreas and a pT2N1M0 ampullary tumor. Postoperative period was complicated with a Grade B/C pancreatic fistula that was managed by percutaneous drainage of the fluid collection. Conclusion: Circuportal pancreas is a rare anomaly complicating pancreatic surgery.