An intraluminal papillary epithelial neoplasm arising within the ducts. Representative examples are the intraductal breast papilloma and the salivary gland intraductal papilloma. The disease is intraductal papilloma (MONDO_0002060). Also known as: duct adenoma, duct papilloma, ductal papilloma, intraductal papilloma (morphologic abnormality).