Diagnostic Considerations
The differential diagnosis of primary sclerosing cholangitis (PSC) includes congenital diseases (eg, Caroli disease, choledochal cysts) and secondary cholangiopathy, as observed in patients with collagen vascular diseases (eg, systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis) and in those with infiltrative diseases (eg, mediastinal fibrosis, Riedel thyroiditis, eosinophilic cholangitis, histiocytosis X). Infectious causes from parasitic, fungal, viral, or bacterial infections or from recurrent cholangitis itself, especially in patients who are immunocompromised, can cause multifocal liver abscesses that lead to a PSC-like appearance of the bile duct.
Biliary S100A9 levels may be a useful marker for PSC activity, and its implication in inflammation and carcinogenesis warrants further investigation. [20]
Differential Diagnoses
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Abdominal Vascular Injuries
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Periductal onion skin fibrosis seen in primary sclerosing cholangitis.
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Endoscopic retrograde cholangiopancreatography performed in a patient with abnormal liver function test results shows multiple intrahepatic bile duct strictures and beading.
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Double-contrast barium enema (same patient as in the previous image) shows filiform polyps and an ahaustral colon resulting from ulcerative colitis.
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Percutaneous transhepatic cholangiogram shows dilatation, stricturing, and beading of the intrahepatic bile ducts. Note the surgical clips from a previous cholecystectomy.
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T-tube cholangiogram shows irregularity of the common bile duct, stricturing, beading, and dilatation of the intrahepatic bile ducts. Note a calculus in the termination of the left hepatic duct (arrow).
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Magnetic resonance cholangiopancreatography shows a normal-sized common bile duct, but strictures of both the left and right ducts are noted as well as a dilated proximal left hepatic duct.
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Technetium-99m iminodiacetic acid scan shows retention of the radionuclide proximal to strictures in the distribution of the left hepatic duct. Note the lack of filling of the gallbladder because of a previous cholecystectomy. Isotope has entered the small bowel.
