Caroli Disease and Syndrome: Evidence‑Based Definitions, Diagnosis, and Surveillance

Definition & Classification

Caroli disease is a rare congenital disorder corresponding to Type V choledochal cysts, characterized by segmental saccular or fusiform dilatation of intra‑hepatic bile ducts, whereas Caroli syndrome adds congenital hepatic fibrosis and often renal cystic disease. 1
Histologically, Caroli disease shows isolated bile‑duct dilatation without fibrosis, while Caroli syndrome exhibits bile‑duct dilatation together with hepatic fibrosis, placing it within the autosomal‑recessive polycystic kidney disease spectrum. 3

In Caroli syndrome, portal‑hypertension manifestations (esophageal varices, splenomegaly, portosystemic shunting) predominate due to underlying hepatic fibrosis. 5
The majority of patients with Caroli syndrome have renal cystic lesions, although the severity of renal and hepatic disease does not correlate. 5

Magnetic resonance cholangiopancreatography (MRCP) with contrast‑enhanced sequences is the preferred diagnostic modality, reliably visualizing the biliary tree, demonstrating continuity of cystic lesions with bile ducts, and revealing the pathognomonic “central dot sign.” 1
Contrast‑enhanced computed tomography can be used as an alternative but provides lower accuracy for biliary tree visualization compared with MRCP. 1
Abdominal ultrasound may detect cystic lesions but is limited in fully characterizing disease extent. 1

Endoscopic retrograde cholangiopancreatography (ERCP) should be avoided for diagnostic purposes because it increases the risk of biliary infection in these patients. 2

Non‑invasive liver‑stiffness measurement helps assess hepatic fibrosis and is essential for distinguishing Caroli syndrome from isolated Caroli disease. 3
Renal imaging (ultrasound, CT, or MRI) is recommended to identify associated renal cystic lesions suggestive of Caroli syndrome. 5
Routine genetic testing for PKHD1 mutations is not recommended in clinical practice due to the gene’s size, complex splicing patterns, and interpretive challenges. 4

Beta‑blockers are advised for primary variceal prophylaxis, and endoscopic variceal ligation is employed as needed for bleeding control. 5

Ongoing assessment of renal function is required because renal involvement is frequent in Caroli syndrome. 5

All patients with Caroli disease or syndrome should undergo annual MRCP surveillance for cholangiocarcinoma beginning at diagnosis. 2
The prevalence of cholangiocarcinoma in this population is approximately 7 %, markedly higher than the 0.05 % prevalence in the general population. 2
Serum CA 19‑9 testing has poor diagnostic performance for cholangiocarcinoma screening and is not recommended; definitive diagnosis requires histopathologic confirmation. 2
Reported cholangiocarcinoma recurrence rates after hepatic resection or liver transplantation can reach up to 75 %, although this likely overestimates true recurrence given the overall low incidence. 5

Do not use ERCP diagnostically when MRCP is available, as the infection risk outweighs any diagnostic benefit. 2
Do not underestimate malignancy risk; the 7 % cholangiocarcinoma prevalence mandates lifelong surveillance. 2
Distinguish Caroli disease from Caroli syndrome because the presence of congenital hepatic fibrosis shifts management focus toward portal‑hypertension complications. 4