Pancreatic and extra-pancreatic imaging of autoimmune pancreatitis

Objective To describe the imaging findings of pancreatic and extra-pancreatic lesions of autoimmune pancreatitis (AIP), to improve the imaging diagnostic accuracy of AIP. Methods From 2011 to June 2014, 38 AIP patients according to 2010 international consensus diagnostic criteria for AIP were included. Thirty-six patients underwent contrast enhanced CT scan, 17 patients underwent contrast enhanced MRI, 15 underwent MRCP, and the imaging data were retrospectively reviewed. Results In the 38 patients, the pancreas showed diffuse enlargement in 23, focal enlargement in 9, mixed enlargement in 6. All the patients demonstrated as progressive enhancement and gradually delayed enhancement. Fourteen cases showed diffusely irregular narrowing of the main pancreatic duct. Pseudo-capsule like structure was presented around the lesions in 24 cases. Extra pancreatic lesions included biliary duct involvement in 24 cases, renal lesions in 4 cases, peri-pancreas vessels involvement in 20 cases, 8 cases with enlargement of lymph nodes. Conclusions AIP presents with characteristic imaging features in pancreas and extra pancreatic organs. Imaging tests are helpful in the early diagnosis of AIP. Key words: Pancreatitis; Autoimmune diseases; Tomography, X-ray computed; Magnetic resonance imaging