Pyloric gland-type tubular adenoma superimposed on intraductal papillary mucinous tumor of the pancreas. Pyloric gland adenoma of the pancreas.

We report a rare case of pyloric gland-type tubular adenoma of the main pancreatic duct. It was a grossly visible polypoid nodule and was composed of closely packed pyloric-type glands. This adenoma was present within an intraductal papillary mucinous adenoma (IPMA). In this IPMA lesion, aggregations of pyloric-type glands were occasionally observed, and most of the cells including ductal lining cells expressed pyloric gland-type mucin. The IPMA of the present case showed more extensive pyloric gland metaplasia or differentiation than commonly noted in IPMAs. We consider this pyloric gland-type tubular adenoma to be derived from a selective growth of IPMA cells showing pyloric gland metaplasia.