Pathological comparisons between intraductal tubular adenoma (pyloric gland type; A,D,G,J), gastric-type intraductal papillary mucinous neoplasm (IPMN; B, E, H, K) and intraductal tubulopapillary neoplasm (ITPN; C, F, I, L). Grossly, ITA and ITPN show a polypoid and nodular mass in the dilated pancreatic duct (A, C), whereas IPMN shows a papillary mass in the mucin-filled dilated duct (B). Microscopically, ITA and IPMN comprise closely packed ducts or tubular glands that are lined with cuboidal-to-columnar mucin-secreting cells with abundant cytoplasm and basally oriented nuclei (D, E, G, H). ITPN shows tightly-packed small glands with a tubulopapillary growth pattern without secreted mucin (F). The neoplastic cells show high-grade atypia with scant cytoplasmic mucin. Intraductal necrotic foci are observed (I). ITA and IPMN express MUC5AC robustly and diffusely (J, K) and ITPN expresses MUC1.