Paget's cells. New evidence linking mammary and extramammary Paget cells to a common cell phenotype.

Three mouse monoclonal anti-human cytokeratin antibodies were made against human sole epidermis. One of these (KA4) was shown to react with a variety of human simple epithelium, including eccrine and apocrine sweat glands and the luminal cells of the breast ducts and lobules, but failed to decorate interfollicular stratified squamous epithelium. This antibody reacted by the immunoblot technic with cytokeratins of Mr values 54, 46, and 40 kdaltons. KA4 reacted strongly with clear cells found in 11% of breast epithelium in clinically uninvolved nipples and with all Paget's cells in four cases of mammary and five cases of extramammary Paget's disease. These findings suggest a common cellular phenotype for Paget's cells and relates them to a population of cells found in breast epithelium.