Intraductal tubular adenoma (pyloric gland-type) of the pancreas: a reappraisal and possible relationship with gastric-type intraductal papillary mucinous neoplasm

Aims:  Intraductal tubular adenoma (ITA) is an uncommon intraluminal polypoid lesion that occurs in the main pancreatic duct and involves the main pancreatic duct in the region of head or body. Three cases of ITA are presented, the literature reviewed and their association with intraductal papillary mucinous neoplasm (IPMN) is postulated.
Methods and results:  ITA is composed of tightly packed tubular structures with focal cystic dilation and papillary areas lined by gastric/pyloric epithelium showing minimal to mild cytological atypia. Pancreatic intraepithelial neoplasia (PanIN) 1A and B was present in smaller ducts of all cases. In addition, in the cases in this report and 50% of cases reported in the literature, an associated gastric-type IPMN was present in the same duct as the ITA or in adjacent ducts. The coexistence of ITA and IPMN and the similarities of their epithelial lining (gastric/pyloric mucosa) suggest a possible pathogenic link.
Conclusions:  ITA can occur without (type A) or with (type B) an associated gastric-type IPMN. ITA could represent a localized, polypoid form of gastric-type IPMN.It is a benign lesion with no evidence of invasion and no direct tumour-related deaths. Its relationship to intraductal tubular carcinoma remains to be elucidated.