Gastroenterology and Hepatologymiddle twist
A 42-year-old woman has 18 months of fatigue, pruritus and intermittent discomfort beneath the right costal margin. Alkaline phosphatase is 410 U/L (30–110), alanine aminotransferase 78 U/L (5–40), bilirubin 28 micromol/L (3–20), and antimitochondrial antibodies are absent. Ultrasound shows no biliary dilatation. Magnetic resonance cholangiography demonstrates several short narrowed segments alternating with mildly widened segments throughout the intrahepatic and extrahepatic ducts. Which one of the following is the most likely diagnosis?