Ultrasonographic imaging of bile duct lesions in autoimmune pancreatitis

Patients with autoimmune pancreatitis (AIP) commonly have lesions in the bile duct itself and show stenosis of the bile duct system; however, no detailed study has evaluated the ultrasonographic findings of bile duct lesions in AIP. In this study, we monitored the clinical course and imaging findings, mainly ultrasonographic, of bile duct lesions in AIP.

We retrospectively analyzed the incidence of bile duct lesions, imaging findings, and clinical course in 37 patients with AIP.

Characteristic bile duct and gallbladder wall thickening was recognized on ultrasound in 37.8% (14/37) of AIP patients. We divided the patients into 2 types according to the ultrasonographic findings of bile duct wall thickening: (1) 3-layer type (64.3%) and (2) parenchymal-echo type (35.7%). All 14 cases were treated with prednisolone, with immediate resolution of the bile duct lesions.

Sclerosing cholangitis is one of the extrapancreatic lesions that are commonly detected in AIP patients; it is detected on ultrasonographic imaging as characteristic wall thickening. Our ultrasonographic findings reflect the fact that bile duct wall thickening in AIP is an inflammatory process that responds to prednisolone therapy. Ultrasonography is a useful tool in detecting biliary tract lesions in AIP.