Caroli’s disease

Clinical History

The patient presented with pain in her abdominal right upper quadrant for one month.

Imaging Findings

The patient presented with pain in her abdominal right upper quadrant for one month. Laboratory test showed midly elevated serum alkaline phosphatase and gamma-glutamylpeptidase. Serum total bilirubin and creatinin were normal. Renal parameters and the chest radiograph were normal.
Contrast-enhanced CT revealed cystic dilatation of the larger intrahepatic ducts, but no stones had been confirmed. The common bile duct and gall bladder were normal.

Discussion

Caroli disease is a rare congenital disorder of the intrahepatic bile ducts. It is characterized by intrahepatic dilatation of the biliary tree, thought to be the result of a pathologic developmental process known as a ductal plate malformation (DPM)[1]. Caroli disease is often associated with autosomal recessive polycystic kidney disease (ARPKD), and both the hepatic and renal processes are thought to reflect a developmental process, albeit in the context of different organs. The term Caroli disease is applied if the hepatic disease is limited to ectasia or segmental dilatation of the larger intrahepatic ducts. This form is much less common than Caroli syndrome, in which malformations of smaller bile ducts and congenital hepatic fibrosis are also present.
In Caroli disease, DPM occurs at the level of the larger intrahepatic ducts (left and right hepatic ducts, segmental ducts), resulting in dilatation and ectasia. The resulting biliary stasis may lead to cholelithiasis, cholangitis, and sepsis, as well as an increased risk of cholangiocarcinoma[2]. In Caroli syndrome, DPM occurs at all levels of bile duct formation. In the more peripheral biliary tree, DPM is associated with portal vein malformations as well as fibrosis of the portal tracts or fibrous bands extending across adjacent portal tracts. These findings are typical of congenital hepatic fibrosis (CHF); therefore, Caroli syndrome is thought to exist in the same spectrum of disease as CHF [2].

Plain radiography of the abdomen may very rarely reveal small intrahepatic bile duct calcifications. Cholangiography is best suited to depict the multiple ductal dilatation, called the "lollipop tree" aspect.
The 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 [3] can be easily seen on ultrasound. Complications such as cyst haemorrhage and infection may result in low-level echoes within the cysts and debris–fluid levels. It is important to demonstrate the communication between the cystic ductal dilatation and the bile duct system either by cholangiography or by ultrasound in order to distinguish Caroli’s disease from polycystic liver disease or multiple simple hepatic cysts. Enhanced computed tomography gives not only a strong orientation for the diagnosis of Caroli's disease (segmental dilatation of intrahepatic bile ducts with central dot sign) but may also show many associated anomalies (liver dismorphy in congenital hepatic fibrosis, renal anomalies) proving to be a powerful diagnostic tool.
MR imaging provides information about the severity, location, and extent of liver involvement. MRC can be proposed as unique modality in diagnostic evaluation of patients with Caroli's disease[4], and it can completely replace ERCP, as it provides all the necessary information for therapeutical planning.

Differential Diagnosis List

Final Diagnosis

Caroli’s disease

URL:	https://www.eurorad.org/case/2883
DOI:	10.1594/EURORAD/CASE.2883
ISSN:	1563-4086