Extramammary Paget's cells: further evidence of sweat gland derivation.

Tissue from a 66-year-old male patient with extramammary Paget's disease of the right side of the scrotum and the right groin was studied for the presence of several antigens with the immunoperoxidase technic. Adenokeratin (cytokeratin No. 18) and carcinoembryonic antigens were positive in Paget's cells, whereas squamokeratin (cytokeratin No. 10) was expressed only in normal epidermal cells. Langerhans cells were decreased in the region of the tumor. Many transferrin receptors were present on the tumor cells, indicating a high cellular proliferation rate. Enzyme histochemical studies of the extramammary Paget's cells showed positive reactions for several enzymes typical of sweat glands, except for leucine aminopeptidase, which was negative. A comparison with three other cases showed that these enzyme reactions varied greatly from case to case. Both immunohistochemical and enzyme histochemical findings provide further evidence that extramammary Paget's cells are related to sweat gland epithelial cells, with variable expression of cellular characteristics.