Postnatal diagnosis of choledochal cyst following cholangitis: the critical role of imaging

Abstract Choledochal cysts (CCs) are rare congenital anomalies of the biliary tree, usually diagnosed prenatally and rarely during infancy or early childhood. While many cases present with non-specific symptoms, cholangitis may be an early clinical manifestation, prompting further diagnostic evaluation. Imaging plays a pivotal role in identifying CCs, with ultrasonography often serving as the first-line modality and magnetic resonance cholangio-pancreatography (MRCP) providing detailed characterization. This case report discusses the postnatal diagnosis of a Todani type IVa choledochal cyst in a 4-year-old child following an episode of cholangitis. After characterization through imaging, the patient underwent excision of the extrahepatic bile duct and subsequent hepaticojejunal anastomosis. No postoperative complication occurred and the patient was found to be in good clinical condition at follow-up. The aim of this case report is to emphasize the importance of recognizing cholangitis as a diagnostic clue and the essential role of imaging for accurate diagnosis and surgical planning.