Periampullary duodenal duplication cyst masquerading as a choledochocele.

Enteric duplication cysts are rare congenital anomalies of unclear etiology. While they can occur anywhere in the gastrointestinal tract, they typically occur in the ileum or ileocecal region and very rarely in the duodenum. Here, we report a case of a periampullary duodenal duplication cyst in a 13-year-old male who presented with clinical and laboratory evidence of small bowel obstruction, hepatitis, and pancreatitis. Based on radiologic imaging, the patient was thought to have a type III choledochal cyst (choledochocele) within the duodenal lumen. Intraoperative findings and postoperative pathological evaluation, however, revealed that the lesion was a duodenal duplication cyst masquerading as a choledochal cyst. Interestingly, the duplication cyst was communicating with the common bile duct, simultaneously causing biliary and small bowel obstruction.