Imaging description

A seven-year-old boy presented with nausea, right upper abdominal pain, and jaundice. An initial ultrasound (not shown) demonstrated a cystic lesion in the area of the porta hepatis, separate from the gallbladder. Axial and coronal T2-weighted MR images and 3D MRCP demonstrated fusiform dilatation of the central hepatic ducts and the common bile duct, consistent with a type I choledochal cyst (CC) (Fig. 45.1a–k). The intrahepatic bile ducts appeared normal in caliber. There was no evidence for choledocholithiasis or pancreatitis. An endoscopic retrograde cholangiopancreatography (ERCP) confirmed contrast filling of a fusiform dilated common bile duct without associated dilatation of the intrahepatic bile ducts (Fig. 45.1).

Importance

CCs represent congenital dilatation(s) of the extrahepatic and/or intrahepatic biliary system. The initial diagnostic workup usually entails an abdominal ultrasound, which demonstrates an anechoic cystic structure in the region of the porta hepatis, separate from the gallbladder. Depending on the extent of the cyst, five different types are recognized according to the classification system of Todani (Fig. 45.2). Type I is the most common type, comprising 80–90% of CCs, and representing a fusiform or cystic dilatation of the extrahepatic biliary system. A mild, secondary dilatation of the more proximal intrahepatic biliary system may be visualized; however, the more peripheral intrahepatic bile ducts are typically not dilated.