Caroli disease is a rare inherited disorder characterized by dilation of the intrahepatic bile ducts. There are two types of Caroli disease, the most common being the simple, or isolated case where the bile ducts are widened by ectasia. The second, more complex, cause is commonly known as Caroli Syndrome. This complex form is also linked with portal hypertension and congenital hepatic fibrosis. The differences between the causes of the two cases have not yet been discovered. Caroli disease is also associated with liver failure and polycystic kidney disease. The disease affects about 1 in 1,000,000 people, with more reported cases of Caroli syndrome than of Caroli disease.