Choledochal cyst

Choledochal cysts are rare cystic dilations of the bile ducts They are believed to be congenital (from birth) and are associated with biliary obstructions in infants. Remaining asymptomatic into adulthood is rare, but not unheard of. Choledochal cysts lead to an increased risk of biliary cancer and are considered pre-malignant. The risk of cancer developing is dependent on age from 2% at age 20, to 75% at age 70.There are 5 different types of choledochal cysts.- Type I - the most common, which relates to dilatation of the extrahepatic common bile duct.- Type II - a diverticulum arising from the extrahepatic bile duct.- Type III - dilatation of the extrahepatic duct within the duodenal wall.- Type IV - Second most common with dilatations and cysts of intra and/or extrahepatic ducts.- Type V - Multiple dilatations and/or cysts of intrahepatic ducts only. This is also known as Caroli disease.