Choledochal dilatation

Localization Gall bladder Dilation Choledochal duct Intrahepatic bile ducts... 

A choledochal cyst is a dilatation of the common bile duct that presents with neonatal jaundice (Fig. 4.3). They are more frequent in females and in the Asian population with a worldwide frequency of 1 15,000. Many theories regarding the etiology of choledochal cysts have been proposed (Gazelle et al. 1998). In the neonate a congenital etiology has been proposed, while in older children it is thought to be secondary... 

Type III Cystic dilatation of the intramural portion of the common bile duct and is contended by some to represent a duodenal diverticulum rather than a choledochal cyst. 

On US a choledochal cyst will be seen as a cystic lesion with a thin wall, well defined borders, and echogenic material inside the cyst that corresponds to biliary sludge. However, it is important in the US evaluation to determine if the cyst is really a dilated choledochus, if the intrahepatic ducts are compromised, and if there is portal hypertension. As US has shown a specificity of 97% for choledochal cysts, it is widely used as the first diagnostic tool (Gubernick et al. 2000 Teele and Share 1991). 

Fig. 4.3a-e. Choledochal cyst dilatation, a-c Cystic dilatation of the CBG at successive caudad levels (type 1). d Cystic dilatation noted on 99Tc-lDA scan, e Cystic dilatation of an intrahepatic duct (type 111)... 

Fig. 4.4. a Classification of choledochal cysts. b,cCT demonstrates multiple cystic dilatation (saccular), signifying Caroli s... 

Biliary tract In three ketamine abusers with recurrent epigastric pain the common bile ducts were dilated, mimicking choledochal cysts on imaging [42 ]. 

Wong SW, Lee KF, Wong J, Ng WW, Cheung YS, Lai PB. Dilated common bile ducts mimicking choledochal cysts in ketamine abusers. Hong Kong Med J 2009 15 (1) 53-6. 

A choledochal cyst is a rare congenital dilation of the hepatic duct of the liver and is due to a ductal plate malformation of the large hile ducts. They maintain continuity with the biliary tree. These cysts can he intrahepatic and/or extrahepatic (Kim et al. 1995). 

The type 1 is the most common type, making up about half of all choledochal cysts. This type is a cystic dilation of the extrahepatic biliary duct. 

At imaging the shape of the choledochal cyst depends on the type, appearing as a fusiform or cystic dilatation of the bile duct. For example, the type 1 cyst appears as a fusiform dilatation of the common duct. 

The incidence of malignancy in choledochal cysts is reported at between 10%-30%. The pathogenesis of CCA in choledochal cysts may be caused by the carcinogenic effect of pancreatic reflux. This complication is especially encountered with the most common type 1 cysts of the Todani classification, which consists in cystic, focal or fusiform dilatation of common bile duct. On the other hand, type 111 cysts rarely undergo malignant changes. 

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