GI Radiography

Imaging Findings

Study shows dilated biliary radicles, with the central dot sign. The common bile duct is normal. Ascites with right sided pleural effusion is seen. Liver biopsy showed hydropic degeneration with associated chronic active hepatitis.

Diagnosis:

Caroli's syndrome (Type II)

Discussion:

Caroli's Disease (CD) first described in 1958 by Jacques Caroli as communicating cavernous ectasia of the biliary tree is an uncommon cause of chronic, often lifethreatening hepatobiliary disease. CD is a rare condition characterized by non-obstructive saccular or fusiform dilatation of the intrahepatic bile ducts usually manifested in childhood, thought to be congenital and presumably of autosomal recessive hereditary character. Caroli described two types: Type 1- the rare isolated variety characterized by recurring episodes of cholangitis. The more frequently occurring Type 2 is associated with congenital hepatic fibrosis, and consequently there are also symptoms of portal hypertension.

Both types may make their first appearance at a very early age. Diagnosis can be done non-invasively with hepatobiliary scintigraphy, ultrasound and echo-doppler. These dilated sacculi or cystic spaces appear as anechoic areas on ultrasound, and are hypodense on CT. The fibrovascular bundles containing portal vein radicals and a branch of the hepatic artery bridging the saccule appears as a central dot or a linear structure on CT, enhancing with contrast. This "central dot sign" described on CT can be easily seen on ultrasound. In Caroli's syndrome both CT and ultrasound show focal mild dilatation of intrahepatic bile ducts (2-3 mm). The liver shows changes of portal hypertension (shrunken liver, splenomegaly, splenic and esophageal varices and ascites).

Caroli's disease may be associated with choledochal cysts, medullary sponge kidney, infantile and adult polycystic kidney disease and cystic renal dysplasia. Cholangiocarcinoma may be a complication. Cirrhosis of liver mimics this condition and can be differentiated by biopsy where there will be hepatocellular dysfunction. Caroli's disease is sometimes included in the classification of choledochal cyst, which is not appropriate since choledochal cysts occur in extra hepatic bile ducts and there is no renal involvement.

The threats of this condition are: cholestasis, cholangitis, intrahepatic lithiasis, hepatic failure, and cholangiocarcinoma. Treatment of the localized form includes lobectomy. In diffuse disease, treatment may be medical with antibiotics and sometimes bile solvents. In case of failure, transplantation may be entertained. Therapy using Ursodeoxycholic acid (10 mg/kg/day) is indicated for intrahepatic stones in Caroli's syndrome. Patients must be followed closely for many years to ensure that the intrahepatic ducts do not remain dilated and that cholangitis do not recur.