The diagnosis can be made when there are classical imaging features in the correct clinical context, and secondary causes of cholangitis have been excluded 16.
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 .
The average age of diagnosis is 54 years (range 6-93) with increased occurrence in men (63.2%) 15. A large number of asymptomatic individuals are identified upon investigation of persistently deranged liver function tests. Symptomatic individuals commonly present non-specifically with fatigue. More specific symptoms include pruritus, jaundice or GI bleeding 16.
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
- Sjogren syndrome 6
- retroperitoneal fibrosis 6
- mediastinal fibrosis
- Riedel thyroiditis
- orbital pseudotumour
Unlike primary biliary cirrhosis, antibody titers 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 characterized 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 is able to demonstrate both the changes of cirrhosis and irregularity of bile duct caliber. Additionally, brightly echogenic portal triads may be visible.
- 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 caliber 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
Treatment and prognosis
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 .
- cholangiocarcinoma develops in ~15% patients 6
colorectal cancer 14
- 4x greater risk compared to IBD patients without PSC
- 10x greater risk compared to general population
- hepatocellular carcinoma: appears to be not increased beyond other causes of cirrhosis 14
General imaging differential considerations include:
cirrhosis from other causes
- caudate lobe not as frequently or as markedly enlarged
- left lobe usually also hypertrophied
- secondary sclerosing cholangitis
- cholangiocarcinoma (can also occur as a later complication)
primary biliary cirrhosis
- especially difficult to distinguish when PSC is limited to intrahepatic biliary tree
- young women more frequently affected
- high antibody titers 4
- Alagille syndrome (arteriohepatic dysplasia)
- hepatic sarcoidosis: see abdominal manifestations of sarcoidosis
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