PSC is believed to develop due to inflammation of the bile ducts (cholangitis), with consequent stricturing (i.e. narrowing) and hardening (sclerosis) of these ducts due to scar formation, be it inside and/or outside of the liver. The resulting scarring of the bile ducts obstructs the flow of bile, which further perpetuates bile duct and liver injury.
Primary sclerosing cholangitis is associated with cholangiocarcinoma, a cancer of the biliary tree, for which the lifetime risk among patients with PSC is 10-15%. This represents a 160-fold greater risk of developing cholangiocarcinoma compared to the general population. Surveillance for cholangiocarcinoma in patients with PSC is encouraged, with some experts recommending annual surveillance.
Because many PSC patients have no symptoms, the disease is often discovered through abnormal results on routine liver blood tests. Formal diagnosis is usually made by cholangiography, an X-ray test involving injection of dye into the bile ducts, or by a MRI. The itching associated with the disease can be relieved with medication, and antibiotics are used to treat bile duct infections when they occur.