All of the following are risk factors for cholangio carcinoma except:

Primary scierosing cholangitis is characterized by diffuse inflammation and fibrosis of the biliary system with irregular patchy strictures. It can present with jaundice, pruritis, fatigue, and recurrent cholangitis. End-stage liver disease may result in liver transplantation. There is a strong association with inflammatory bowel disease, paicularly pan-ulcerative colitis. Primary sclerosing cholangitis is a strong risk factor for cholangiocarcinoma. Caroli's disease consists of congenital segmental, saccular dilatations of the intrahepatic bile ducts. It is associated with stone formation, recurrent bacterial cholangitis, and cholangiocarcinoma. The parasite clonorchis sinensis can reside in bile ducts for as long as 30 years and can be a risk factor for eholangiocarcinoma. Ascaris lumbricoides may also be a risk factor.