Caroli Disease
Caroli disease is a rare congenital condition characterized by abnormal dilation of the larger bile ducts inside the liver. It is part of a broader group of “ductal plate malformations” and can occur in two main forms: simple Caroli disease, in which only the bile ducts are abnormally dilated, and Caroli syndrome, in which the dilation is associated with congenital hepatic fibrosis and often with polycystic kidney disease. Caroli disease typically presents in childhood or young adulthood with recurrent bile duct infections (cholangitis), and it carries an increased lifetime risk of cholangiocarcinoma. Imaging—particularly MRI with MR cholangiopancreatography (MRCP)—is central to diagnosis.
What is it?
Caroli disease is a rare congenital condition in which the larger bile ducts inside the liver are abnormally dilated. Unlike simple cysts of the liver, these dilations directly communicate with the rest of the biliary tree, which means bile flows through them. Areas of dilation may be saccular (pouch-like) or fusiform (spindle-shaped) and can affect part of the liver or be diffusely distributed throughout both lobes. Bile flow within these dilated ducts is often sluggish, predisposing to bile stagnation, stone formation, and recurrent infection.
Caroli disease is recognized in two main forms. Simple Caroli disease (often just called “Caroli disease”) refers to dilation of the bile ducts without other structural liver abnormalities. Caroli syndrome refers to dilation of the bile ducts in combination with congenital hepatic fibrosis—a related condition in which the liver contains abnormal connective tissue around the small portal tracts. Caroli syndrome is significantly more common than simple Caroli disease and tends to present with both biliary complications and signs of portal hypertension (such as enlarged spleen, variceal bleeding, and low platelet counts). Caroli syndrome is also more strongly associated with autosomal recessive polycystic kidney disease (ARPKD) and other genetic disorders, while simple Caroli disease may occur sporadically or in association with autosomal dominant polycystic kidney disease (ADPKD).
Caroli disease is one of the conditions in the broader group called “ductal plate malformations,” which result from abnormal remodeling of the developing bile ducts during fetal life. Other conditions in this group include biliary hamartomas (von Meyenburg complexes), polycystic liver disease, congenital hepatic fibrosis, and choledochal cysts. Several of these can coexist, and the spectrum reflects different levels at which biliary development is disrupted.
The age at presentation and severity of symptoms vary widely. Some patients are diagnosed in childhood, while others remain asymptomatic for many years and are first identified in adulthood. The most common presentation is recurrent episodes of bacterial cholangitis: fever and chills, upper right abdominal pain, jaundice, and sometimes signs of severe infection such as low blood pressure or confusion. Cholangitis episodes occur because stagnant bile within the dilated ducts becomes a breeding ground for bacteria. Stones often form within these dilated ducts and contribute to further infection and obstruction. Patients with Caroli syndrome often present with signs of portal hypertension—such as enlarged spleen, low platelets, variceal bleeding, or ascites—in addition to biliary symptoms. Patients with associated polycystic kidney disease may have additional kidney-related symptoms or impaired kidney function.
An important long-term concern in Caroli disease is the substantially increased lifetime risk of cholangiocarcinoma, a cancer of the bile ducts. This risk underscores the importance of ongoing surveillance, even in patients with otherwise stable disease.
Diagnosis is based on a combination of clinical assessment and imaging. Ultrasound may show dilated bile ducts and stones. CT with contrast provides detailed information about the extent of biliary involvement, complications, and associated kidney and portal hypertension findings. MRI with MR cholangiopancreatography (MRCP) is the primary tool for characterizing Caroli disease because it can clearly demonstrate the abnormally dilated intrahepatic bile ducts and their communication with the rest of the biliary tree. A classic imaging finding is the “central dot” sign, in which small portal vein branches are seen within dilated bile ducts. Endoscopic retrograde cholangiopancreatography (ERCP) provides direct imaging of the bile ducts and allows therapeutic procedures but is generally reserved for patients in whom intervention is anticipated. Blood tests assess liver function, signs of infection, and kidney function. Genetic testing may be appropriate in patients with associated polycystic kidney disease or familial features and can help guide screening of relatives.
Important to Know
Management of Caroli disease is highly individualized and depends on the extent of biliary involvement, the frequency and severity of complications, the presence and severity of associated conditions (such as congenital hepatic fibrosis and polycystic kidney disease), and overall health. Care is best delivered in centers with experience in complex hepatobiliary disease, and is typically coordinated by hepatologists, hepatobiliary surgeons, gastroenterologists, interventional radiologists, infectious disease specialists, nephrologists (when kidney disease is present), and—when appropriate—liver transplant teams and genetic counselors.
Cholangitis is one of the most important complications and a frequent reason for medical evaluation and hospitalization. Episodes are treated promptly with antibiotics, supportive care, and—when significant obstruction is present—biliary drainage through endoscopic, percutaneous, or surgical approaches. Ursodeoxycholic acid is used in selected patients to help reduce biliary stone formation, although evidence for its benefit varies. Patients with frequent cholangitis episodes may benefit from preventive measures and close follow-up.
When Caroli disease is localized to one part of the liver (such as a single lobe), surgical resection of the affected region can be highly effective and may dramatically reduce the frequency of cholangitis and other complications. For diffuse Caroli disease affecting both lobes—particularly when complicated by recurrent severe cholangitis, end-stage liver disease, advanced portal hypertension, or significant deterioration in quality of life—liver transplantation is often the most effective long-term treatment. Combined liver-kidney transplantation may be considered in patients with significant kidney disease.
Surveillance for cholangiocarcinoma is an important part of long-term care, given the increased lifetime risk. This is typically performed with periodic imaging (often MRI/MRCP) and laboratory testing, with intervals individualized to risk. Patients with new or worsening symptoms—such as significant change in pain pattern, weight loss, or new jaundice—warrant prompt evaluation for malignancy.
Management of associated conditions is also essential. Patients with Caroli syndrome and significant portal hypertension may require treatment for varices, ascites, and other complications, similar to patients with cirrhosis. Patients with polycystic kidney disease require coordinated nephrology care, including monitoring of kidney function, blood pressure control, and, when needed, dialysis or transplantation. Family members of patients with genetic forms of disease may benefit from genetic counseling and screening.
Care is typically coordinated by primary care clinicians and the multidisciplinary teams described above. Imaging and laboratory findings are interpreted alongside the patient’s symptoms, examination, and broader clinical context rather than in isolation. Patient education and clear plans for managing infections, biliary procedures, surveillance imaging, and pregnancy (when relevant) are important components of care.
Red flag symptoms include high fever with chills and abdominal pain (which may indicate cholangitis), rapidly progressive jaundice, severe upper right abdominal pain, vomiting blood or coffee-ground material, black or tarry stools, severe abdominal swelling, confusion or sleep changes, signs of sepsis or shock, or significant unintended weight loss with worsening symptoms. These warrant prompt or urgent medical evaluation, as they may indicate cholangitis, biliary obstruction, variceal bleeding, or other serious complications, including cholangiocarcinoma.