22nd July 2023

Primary sclerosing cholangitis (PSC)

Background

PSC is a condition which is likely to be immune-mediated; however, like AIH and PBC, the exact aetiology is not fully understood.

The disease is characterised by inflammation of the medium and large-sized bile ducts, leading to strictures and progressive fibrosis.

Unlike most other autoimmune related conditions, PSC is much more common in men. There is a strong association with inflammatory bowel disease (IBD), particularly ulcerative colitis. It is important to note that IBD may develop before or after PSC.

Assessment and diagnosis

Many people with PSC are asymptomatic. When present, common presenting symptoms include fatigue, pruritus and upper abdominal pain. In more advanced disease, patients may present with features in keeping with chronic liver disease, for example, jaundice or abdominal distension.

Initial investigations include LFT, which typically shows a cholestatic pattern (raised ALP and GGT). In more advanced disease, bilirubin will also be elevated. There are no diagnostic autoantibodies associated with PSC, however, it may be appropriate to test for these to exclude related conditions like PBC and AIH.

Imaging of the biliary tree is crucial to diagnose PSC. An abdominal ultrasound would be the usual first step, as a non-invasive test to exclude other causes of bile duct disease. CT imaging may show bile duct thickening and/or duct dilatation. However, MRCP is the gold-standard diagnostic modality, and can also provide information about the distribution of disease. ERCP can also be diagnostic, however, is more invasive and carries more risk; therefore, it should only be done if MRCP has not been diagnostic or if there is potential for therapeutic intervention.

The typical features on MRCP are multiple strictures, giving a ‘beaded’ appearance of the intra and extrahepatic ducts.

Liver biopsy is generally not required, if there is enough evidence to support a diagnosis of PSC. Histology itself is not diagnostic but may be helpful to support the diagnosis or assess for alternative or overlapping diseases.

Management

Management includes pharmacological treatment of symptoms, such as cholestyramine for pruritus, and interventional treatments, such as balloon dilatation of dominant strictures. The latter can improve survival, as well as symptoms, in those who are acutely unwell.

It is important to assess for complications, such as hepatic osteodystrophy or osteopenia, and treat these appropriately. Another serious complication of PSC is cholangiocarcinoma, however, there is no consensus on routine screening for this.

For those whose disease progresses to end-stage liver disease, transplantation is the only therapeutic option.