Biliary lesions associated with autoimmune pancreatitis.

BACKGROUND/AIMS: Characteristic radiological features of biliary lesions in patients with autoimmune pancreatitis (AIP) have not yet been identified. METHODOLOGY: Bile duct lesions and their relationships to other clinical findings were assessed in 43 AIP patients. RESULTS: Of the 43 AIP patients, 34 (79%) had bile duct stenosis. In all the 34 patients, the lower bile duct was involved; in 21 of these, only the lower bile duct was involved, and in 13 patients, there was widespread wall thickening of the middle and upper bile duct where stenosis was not obvious on cholangiography. Furthermore, 4 patients with extensive bile duct involvement also had stenosis of the intrahepatic bile duct. All patients with bile duct involvement had involvement of the head portion of the main pancreatic duct. None of the 6 patients with involvement of only the body and/or tail portion of the main pancreatic duct had bile duct involvement. Gallbladder wall thickening was more frequently noted in patients with extensive bile duct involvement (p < 0.01). Serum IgG4 levels were significantly more elevated in patients with extensive bile duct involvement (p < 0.05). CONCLUSIONS: AIP patients with extensive bile duct involvement characterized by widespread wall thickening of the bile duct may have more active disease.