Intraductal carcinoma arising in intraductal papilloma in an axillary lymph node: review of the literature and proposed theories of evolution.

We report a case of an axillary lymph node containing benign glandular lesions, intraductal papilloma with florid and atypical duct hyperplasia, and ductal carcinoma in situ. We propose 2 theories for the development of the intraductal papilloma: from adjacent benign glandular inclusions, or from displaced epithelial cells from a previous intraductal papilloma in the ipsilateral breast. This case identifies yet another etiology for false-positive sentinel lymph nodes morphologically and by immunohistochemistry.