Light micrograph section through a human liver tissue with primary biliary cirrhosis or primary biliary cholangitis. It is a long term liver disease in which the bile ducts become damaged. The disease is progressive and is caused by a build-up of bile within the liver (cholestasis) that results in damage to the small bile ducts that drain bile from the liver. Over time, this pressure build-up destroys the bile ducts leading to liver cell damage.