Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is an uncommon idiopathic inflammatory condition, which affects the biliary tree resulting in multiple strictures and eventual cirrhosis.

The diagnosis can be made when there are classical imaging features in the correct clinical context, and secondary causes of cholangitis have been excluded ref

PSC is strongly associated with inflammatory bowel disease (IBD) (in 70% cases 6), especially ulcerative colitis and thus shares similar demographics: young to middle aged males (≈4th decade) are most frequently affected 4 .

Most patients are men with a mean age of 40 years ref. Patients present with fatigue, pruritus, jaundice although up to 25% may be asymptomatic ref.

Unfortunately no histological findings are pathognomonic for PSC 2. Frequent findings include 2-4:

  • periductal fibrosis (onion skin lesions)
  • periportal eosinophilic infiltrate
  • paucity of ducts
Associations
Complications
Markers

Unlike primary biliary cirrhosis, antibody titres are usually absent or low 4. Liver function tests will usually have a cholestatic pattern with elevated alkaline phosphatase (ALP) and bilirubin 2.

The entire biliary tree (both intra and extrahepatic) may be involved, with multiple strictures scattered along its length. In ~20% only the intrahepatic and proximal extrahepatic bile ducts are involved 4 ;

The end result of PSC is cirrhosis which is usually characterised by a markedly distorted biliary tract with atrophy of the entire liver with the exception of the caudate lobe which is hypertrophied in almost all cases (68-98%) 1-5. Atrophy involving the left lobe is a feature which somewhat distinguishes it from cirrhosis from other causes, in which the left lobe is usually hypertrophied 1.

Ultrasound

Ultrasound is able to demonstrate both the changes of cirrhosis and irregularity of bile duct calibre. Additionally, brightly echogenic portal triads may be visible.

CT
  • contour abnormalities and atrophy (see above)
  • marked caudate lobe hypertrophy
  • the atrophied liver is of lower density than the hypertrophied caudate lobe 1
  • multiple linear discontinuous low density regions representing dilated intra-hepatic bile duct segments 1
MRCP / cholangiography / ERCP

ERCP remains the gold standard for the depiction of the biliary tree, and also offers the ability to perform cholangioplasty if necessary.

The characteristic findings on direct imaging of the biliary tree are 2-3,5:

  • multiple segmental strictures
    • typically short segment
    • intervening segments are of normal calibre or slightly dilated (beading)
  • biliary dilatation: may be present in ~85% of cases 9
    • general: ~35%
    • segmental: ~50%
  • biliary diverticula
  • mural irregularities
  • distortion of the biliary tree due to associated cirrhosis

The only cure available at present is orthotopic liver transplantation (OLT) with 5 year survival rates approaching 80% 10-11.  However there is evidence that PSC may recur in 5-20% of patients post transplantation 10-12.

No medical therapy has stood the test of time, with ursodeoxycholic acid, immunosuppression, chelation and antifibrolytic therapy unable to demonstrate consistent benefits over placebo 8 .

Percutaneous cholangioplasty of dominant strictures is usually performed in a retrograde fashion via ERCP or via a transhepatic approach 6-7 .

Complications

General imaging differential considerations include:

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Article Information

rID: 7007
Synonyms or Alternate Spellings:
  • Primary sclerosing cholangitis (PSC)
  • Sclerosing cholangitis
  • PSC

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