Primary sclerosing cholangitis is a liver disease in which the bile ducts (small tubes through which bile flows from the liver to the gall bladder and intestines) progressively decrease in size due to inflammation and scarring. As a result, bile that is normally carried out of the liver accumulates within the liver, which then damages liver cells. How common is primary sclerosing cholangitis? Although primary sclerosing cholangitis has been considered a rare disease, recent studies suggest that it is more common than originally thought. The disease may occur alone, but frequently exists in association with inflammatory diseases of the colon, such as chronic ulcerative colitis. Primary sclerosing cholangitis affects both sexes, but is more common in men.