MUC5AC and pancreatic intraductal papillary-mucinous neoplasm: Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a mucin-producing and cystic tumour growing inside the pancreatic duct and forming papillary projections (Klöppel et al. 2014; Klöppel and Kosmahl 2001).