Definition

 • A chronic liver disease characterized by inflammation and scarring in the biliary tree.

 • usually, the entire biliary tree is affected, but occasionally only small interlobular bile ducts are affected (small duct PSC).

Epidemiology

 • uncommon. • Seen predominantly in young men with ulcerative colitis. there is a less strong association with Crohn’s Disease.

 • ~70% of patients with PSC also have ulcerative colitis.

 Aetiology

• unknown, although there is a genetic link with certain human leukocyte antigen (HLA) types.

 Pathogenesis

 • Chronic biliary inflammation is followed by fibrotic scarring which narrows the affected bile ducts. Obstruction within the biliary system leads to progressive fibrosis within the liver which terminates in cirrhosis. Biliary stasis also promotes infection and stone formation.

Presentation

• Asymptomatic in its early stages and is often picked up when elevated alkaline phosphatase levels are found in a patient with uC.

Radiology

 • Demonstration of strictures and dilations within the biliary tree on imaging is highly suggestive of PSC.

Macroscopy

 • early PSC usually causes no macroscopic changes. Advanced disease causes a cirrhotic liver with bile staining. Fibrotic biliary strictures may be apparent in the major bile ducts.

 Histopathology

• explanted liver specimens show fibrosis and inflammation in large bile ducts with inspissated bile and stones. there is a biliary pattern of cirrhosis with large, irregular, jigsaw- like nodules of hepatocytes.

• Liver biopsy specimens show variable features, depending on the biopsy site. If the biopsy is taken from an area unaffected by the primary disease, but distal to a large duct stricture, the liver shows features of duct obstruction (i.e. portal oedema with proliferation of bile ductules). If the biopsy comes from an area affected by PSC, then medium- sized bile ducts show periductal oedema and concentric fibrosis, whilst small bile ducts are often completely absent. Copper accumulates in periportal hepatocytes.

Prognosis

 • Progressive liver disease eventually terminating in cirrhosis.

 * Patients are at high risk of bile duct carcinoma, which develops in ~20% of patients and has a very poor prognosis.