Sebaceous gland metaplasia in intraductal papilloma of the breast.

We report here the first case of sebaceous gland metaplasia arising within an intraductal papilloma of the breast of a 70-year-old female. Several lobules and nests composed of clear cells closely resembling sebaceous glands of the skin were discovered within an intraductal papilloma of the breast. Squamous metaplasia was also noted in certain areas of the tumor. Immunohistochemically, the cells of the lobules and nests stained positively for monoclonal antibodies anti-cytokeratin 14 and epithelial membrane antigen. This study confirms a novel type of metaplasia of the breast.