Cysts Choledochal

Arteriohepatic dysplasia Caroli s syndrome Bile-duct atresia Choledochal cyst... 

Cholecystitis Lithiasis Choledochal cyst Pancreatitis Extraabdominal... 

Fig. 1.78. Choledochal cyst. Transverse US scan through the liver shows a cystic mass (C) in the porta hepatis. Hepatobiliary scintigraphy confirmed communication of the cystic structure with the biliary system. P, portal vein...

Antenatally, US is a useful tool for detection of biliary malformations. The presence of a cystic structure localized at the hepatic hilum can occur in BA or may present as a choledochal cyst. However, if this cyst is small and anechoic it will be more suggestive of an atresia of the biliary canals, while the presence of an echoic cyst that gradually increases in size supports a choledochal cyst. The specificity of these US findings with BA, however, is not well known (Kim et al. 2000). 

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). 

Endoscopic retrograde cholangiopancreatography (ERCP) is an excellent tool that affords good visualization of the biliary ducts, and the extent of the choledochal cyst. However, in pediatric patients, and especially in the very young, it can be a challenging procedure, with an unsuccessful outcome in 5%-30% of all patients. 

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... 

In some instances neither US nor CT can determine whether the cyst has communication with the biliary tract. Scintigraphy with 99tc at 30 min, 6 h, and 24 h could then be used. The sensitivity of the examination maybe as high as 100% for type 1 cysts or as low as 66% for type IV cysts. However, scintigraphy will not delineate the intrahepatic compromise by choledochal cysts (Lam et al. 1999). 

Magnetic resonance cholangiography (MRCP) T2-weighted sequences provide an evaluation of the intra- and extrahepatic bile ducts. Other sequences such as a T1 post-contrast injection provide fine detail on the periportal spaces, parenchyma, and blood vessels. Visualization of the entire biliary tree and the choledochal cysts using MRCP has been reported (Krause et al. 2002). MRCP provides information for the operative planning with less potential risks than ERCP or percutaneous transcutaneous cannulation (PTC). 

Cyst excision and hepaticoenterostomy is the definitive treatment of the disease, and will reduce the 20-fold risk of biliary carcinoma with choledochal cyst. Infants with choledochal cyst may present with the classic triad of jaundice, pain, and right upper quadrant mass however, this is true only in 15%-20% of cases. Usually, only one of the triad will be present. Ascites, liver dysfunction, and coagulopathy may be found in some patients with progressive disease and without treatment (Behrman et al. 2004). 

Since the tumor arises in the intrahepatic ducts, intrahepatic cyst, gallbladder, extrahepatic ducts, or in a choledochal cyst, jaundice will develop in 60%-80% of patients. Other manifestations include vomiting, fever, and abdominal distension (Roebuck et al. 1998). 

MRCP is a very useful imaging tool used to identify possible etiologies of pancreatitis such as abnormal union of the pancreatobiliary junction, choledochal cyst, or pancreas divisum, in patients with unknown cause (Arcement et al. 2001 Hirohashi et al. 1997). 

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). 

Choledochal cysts have been classified by Modani into five types ... 

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. 

Choledochal cysts present water echogenicity/ density/intensity in sonography, CT, or MR. In CT and MR, coronal or reformatted imaging shows better the shape and nature of the biliary anomaly. 

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. 

Kim SH, Lim JH,Yoon HK,et al (2000) Choledochal cyst comparison of MR and conventional cholangiography. Clin Radiol 55 378-383... 

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