Duodenal duplication cyst extending into the posterior mediastinum

•Gastrointestinal tract duplication cysts as congenital malformations.•Duodenal duplication cyst extending into the posterior mediastinum.•It can be misdiagnosed even in surgery.

IntroductionDuodenal duplication is a rare congenital malformation. Although more frequent in childhood, it is rarely observed in adulthood. Preoperative diagnosis can be difficult.Presentation of caseWe report a case of 42 year-old woman with duodenal duplication cyst situated in the posterior mediastinum, who was misdiagnosed even after a primary surgery. Detailed diagnostic workup and a second operation was done.DiscussionThis article discusses the incidence of duodenal duplications, their types and clinical presentations, the radiologic and diagnostic features with different therapeutic options.ConclusionDuodenal and the other intestinal duplication cysts should be considered in the differential diagnosis of oral contrast enhanced intrathoracic lesions in thorocoabdominal computerised tomography imaging.