Intraductal tubular adenomas (pyloric gland-type) of the pancreas: clinicopathologic features are similar to gastric-type intraductal papillary mucinous neoplasms and different from intraductal tubulopapillary neoplasms

BACKGROUND: Intraductal tubular adenoma of the pancreas, pyloric gland type (ITA), is an infrequent intraductal benign lesion located in the main duct and large branch duct of the pancreas. The purpose of this report is to introduce seven new cases and to compare their clinicopathologic features and KRAS mutations to gastric-type intraductal papillary mucinous neoplasms (IPMNs) and intraductal tubulopapillary neoplasms (ITPNs). METHODS: Clinical findings, morphologic features, immunophenotypes and KRAS alterations were investigated in 7 patients with intraductal tubular adenomas, 16 patients with gastric-type intraductal papillary mucinous neoplasms and 6 patients with intraductal tubulopapillary neoplasms. RESULTS: There were more female patients in the ITA and gastric-type IPMN groups, whereas the opposite pattern was observed in the ITPN group. ITAs and gastric-type IPMNs were lined by columnar cells, similar to pyloric glands, with large extracellular deposits of mucin. ITPNs were polypoid and papillary mass located in the pancreatic ducts, which did not show large deposits of mucin. All ITAs and gastric-type IPMNs expressed MUC5AC strongly and diffusely, and 3/6 ITPNs expressed MUC5AC focally and weakly. KRAS mutations were identified in 4 ITAs (4/7, 57%), 9 IPMNs (9/16, 56%) and 2 ITPNs (2/6, 33%). CONCLUSION: The intraductal tubular adenoma should not be considered a precursor lesion of intraductal tubulopapillary neoplasms. No adequate data established ITA should separate as a specific entity from IPMNs. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_172