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Common primary sclerosing cholangitis (PSC) exam questions for medical finals, OSCEs and MRCP PACES

 

Question 1.

What investigations are indicated if there is a suspicion of PSC?

  • Blood tests:
    • Liver function tests
      • In PSC will usually show an elevated alkaline phosphatase, bilirubin and transaminases but these can all be in the normal ranges
    • Autoimmune profile
      • A range of autoantibodies can be present in PSC including smooth muscle (SMA), ANCA and ANA
      • AMA (antimitochondrial) are usually absent in PSC
    • Full liver screen (see chronic liver disease section) to rule out other causes of cirrhosis
  • Imaging:
    • Ultrasound liver
      • Not usually diagnostic and can be normal. Gallstones and gallbladder thickening can be seen.
    • Magnetic resonance cholangiopancreatography (MRCP)
      • This has become the diagnostic imaging of choice and is has none of the associated morbidity of ERCP.
      • Sensitivity > 80% and specificity >87% for PSC diagnosis
      • Classically an ‘onion-skin’ appearance is seen but appearances are often non-specific
  • ┬áLiver biopsy:
    • A biopsy is not needed for diagnosis of PSC.
    • Histological changes are often non-specific, especially in the early stages.
    • Liver biopsy is performed if MRCP and subsequent ERCP are non-diagnostic.

Question 2.

What are the classical sclerosing cholangitis (PSC) findings on MRCP?

  • Unfortunately no histological findings are pathognomonic for PSC. Frequent findings include:
    • Periductal fibrosis (onion-skin lesions)
    • Paucity of ducts
    • Periportal eosinophilic infiltrate