Introduction: Duodenal duplications are rare congenital malformations whose revealing signs are highly variable and nonspecific.
Observation: We report the case of a female infant who presented with neonatal acute pancreatitis complicated by recurrent ascites, profound hypoalbuminemia responsible for pleural and pericardial effusions, revealing a duodenal duplication cyst. The unusual and original clinical presentation as well as the difficulty detecting the duplication radiologically delayed the diagnosis.