Immunohistochemical distinction of Paget's disease from Bowen's disease and superficial spreading melanoma with the use of monoclonal cytokeratin antibodies.

The differentiation of Paget's disease from Bowen's disease and Pagetoid superficial spreading melanoma may represent diagnostic difficulties. The special stains used in their differential diagnosis are nonspecific and not always sensitive. Therefore, the expression of cytokeratins of different molecular weights (54, 57, and 66 kilodaltons [kD]) was studied in 26 intraepithelial neoplasms in formalin-fixed paraffin-embedded tissues with the use of an avidin-biotin complex (ABC) method with monoclonal cytokeratin antibodies. These included 9 cases of Paget's disease, 11 cases of Bowen's disease, and 6 cases of Pagetoid superficial spreading melanoma. Paget cells from vulva and breast were always positive for 54-kD cytokeratin, variable for 57-kD cytokeratin, and negative for 66-kD cytokeratin. The neoplastic cells in all 11 cases of Bowen's disease were stained for 57-kD and 66-kD cytokeratins but not for 54-kD cytokeratin. The neoplastic cells in all cases of melanoma did not express any of the cytokeratins studied. The results indicate that antibodies to cytokeratins of different molecular weights may be used as a diagnostic tool in the distinction of Paget's disease from Bowen's disease and melanoma.