Pancreatic Intraepithelial Neoplasia

The pancreatic intraepithelial neoplasia (PanIN) nomenclature and classification system, used to describe the microscopic epithelial precursor lesions of pancreatic ductal adenocarcinoma, replaced at least 70 different diagnostic terms for the same entities. The average time taken for the genetic progression from an initiating mutation in a normal ductal epithelial cell, through PanIN, to invasive ductal adenocarcinoma has been estimated to be 11.7 years. This chapter discusses the recently introduced two-tier classification, and the microscopic features, of PanIN, together with the differential diagnosis, including intraductal papillary mucinous neoplasia and cancerization of ducts.