Chronic pancreatitis and the differential diagnosis versus pancreatic cancer

Context.-Distinguishing chronic pancreatitis from pancreatic ductal adenocarcinoma (PDAC) is a well-known challenge, at both the clinical and the morphologic level. Objective.-To focus on the histopathologic findings that are diagnostic or suggestive of PDAC. Data Sources.-Findings that are specific to PDAC are the presence of duct structures in perineural and vascular spaces and ("naked") ducts in fatty tissue. However, these findings are only observed in specimens containing extrapancreatic tissue. The features that are suggestive of PDAC in specimens from the pancreas include haphazard distribution of ductlike structures (ie, loss of a lobular pattern), markedly irregular ductal contours, ruptured ducts, nuclear enlargement, pleomorphism and hyperchromatism, and mitotic figures. Immunohistologic markers that are helpful are carcinoembryonic antigen, MUC1, p53, and Ki-67/ MIB1. Conclusions.-There are a few features that are diagnostic and a number that are suggestive of PDAC. Therefore, a combination of several features may be required to clearly distinguish chronic pancreatitis from invasive PDAC.