[Extramammary Paget's disease. Immunocytochemical study and histogenetic considerations].

We report a case of extramammary Paget's disease arising in the anogenital region in association with an underlying sweat gland microcarcinoma. Paget's cells were investigated with monoclonal anti-EMA and anti-cytokeratin antigen and with mono- and polyclonal anti-CEA antigen. Positive immunostaining was observed in Paget's cells and in the underlining tumor, whereas keratinocytes and melanocytes did not stain. CEA was also detected in cells and secretions of normal apocrine glands. The immunohistochemical use of polyclonal anti-keratin and anti-S-100 protein antigen is helpful in differentiating Paget's disease from other morphologically similar skin lesions, such as Bowen's disease and superficial spreading melanoma in situ.