Since certain morphological features of these tumors, especially intraductal papillary growth pattern, are also similar to those of IPMN of the pancreas, Zen et al. [8] proposed that they, together with tumors with macroscopically visible mucin secretion, may belong to a single tumor entity named IPNB. The gene discussed is MUC5AC; the disease is pancreatic intraductal papillary-mucinous neoplasm.