MUC5AC and pancreatic intraductal papillary-mucinous neoplasm: PDAC has been reported to arise from a variety of precancerous lesions, notably pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasia (IPMN)—which both present as mucin-producing epithelia involving branches and ducts—and mucinous cystic neoplasia (MCN), which adopt a cystic shape.3