This case report describes a unique variant of a duodenal duplication cyst in an 8-year-old boy who had recurrent episodes of upper abdominal pain. Imaging revealed a stone-containing cyst near the biliaropancreatic ducts and concomitant hydrops of the gallbladder. Open transduodenal marsupialization of the cyst and resection of the inflamed gallbladder were performed. Further episodes of pancreatitis did not occur for a follow-up of 2 years.