Clinical and pathological characteristics of cystic lesions of extrahepatic bile duct in neonates

Aim: To investigate the differences in clinical and pathological manifestations between biliary atresia with extrahepatic biliary cyst and choledochal cyst in neonates. Methods: Symptoms and clinical signs in 5 neonates with biliary atresia with extrahepatic biliary cyst (4 of type I and 1 of type III) and 17 neonates with choledochal cyst were recorded. The levels of serum alkaline phosphatase, bilirubin, direct bilirubin, transaminase, gamma‐glutamyl transpeptidase were analysed. Width and length of gallbladder and choledochal cyst were measured on B‐mode ultrasound before surgery. Intrahepatic or extrahepatic biliary ducts were visualized with intraoperative cholangiography. The pathologic features in specimens of the liver were studied with light‐ and electron transmission microscopy. Results: All malformations occurred more commonly in girls, and obstructive jaundice was the main manifestation in both groups. Laboratory tests showed similar results for all patients in this study. With regard to pathological features, no significant difference was seen in either light microscopy or transmission electron microscopy, but it was shown with ultrasound that the length and width of the cysts and the gallbladder in neonates with biliary atresia were all shorter than the measurements in patients with choledochal cyst. The intrahepatic bile ducts could not be visualized on intraoperative cholangiography in type III biliary atresia. Deformation of the biliary ducts within the liver and stricture of the portal bile duct were the predominant features in type I biliary atresia, while the bile duct within the liver was normal or dilated in neonates with choledochal cyst. Conclusions: Cystic lesions of the extrahepatic bile duct might be a common manifestation of biliary atresia and choledochal cyst. Intraoperative cholangiography is a precise and effective technique in the differential diagnosis of those lesions and helps decide on the most rational method of treatment.