Differentiation between autoimmune pancreatitis and pancreatic carcinoma based on endoscopic retrograde cholangiopancreatography findings

We have reviewed the endoscopic retrograde cholangiopancreatography (ERCP) images of patients with autoimmune pancreatitis (AIP) and pancreatic carcinoma (Pca) in an attempt to identify findings that would facilitate making a differential diagnosis between AIP and Pca.The study cohort consisted of 39 patients diagnosed with AIP and 62 patients diagnosed with Pca. The ERCP findings in the pancreatic duct and biliary tract were compared between the two groups.The ERCP images revealed that AIP patients had a higher prevalence of narrowing of the main pancreatic duct (MPD) for ≥ 3 cm of its length and a higher prevalence for the presence of side branches in the narrowed portion of the MPD than Pca patients (p0.001 and p0.001, respectively). In contrast, the prevalence of an upstream MPD having a maximal diameter ≥ 4 cm was significantly higher in the Pca patient group (p0.001). The discriminant analysis identified three significant factors: (1) whether or not side branches were present; (2) total length of the narrowed portion of the MPD; (3) maximal diameter of the upstream MPD. It was impossible to differentiate Pca from AIP in the two Pca patients in whom ERCP revealed both narrowing of the MPD for5 cm of its length and the presence of side branches.Among our patient cohort, the ERCP findings in terms of the length of the narrowed portion of the MPD, the presence of side branches, and maximal diameter of the upstream MPD enabled differential diagnosis between AIP and Pca in most of the cases. However, it must be borne in mind that some Pca patients have ERCP findings similar to those of AIP patients.