A peculiar form of multiple cystic dilatation of the intrahepatic biliary system found in a patient with biliary atresia.

The authors report a peculiar form of intrahepatic multiple cysts of the biliary system in a patient with biliary atresia (BA). An 11-year-old girl was admitted to our institution to be investigated for repeated cholangitis occurring after the age of 10 years. She underwent a hepaticojejunostomy, caused by Type I (cyst-type) BA, in the neonatal period. The radiological examination results showed multiple cystic dilatation of the intrahepatic biliary system with a vascular structure protruding into the cyst lumen. Such cystic dilatation with a protruding vascular structure has been noted in patients with Caroli's disease and congenital hepatic fibrosis, and ductal plate malformation is shown to be responsible for the cyst formation. The authors postulate that such malformation of the intrahepatic biliary system is related to the cyst formation in our case.