Cytokeratin 7 (CK7) and Cam 5.2 are often used to differentiate extramammary Paget's disease (EPD) from squamous cell carcinoma (SCC) in situ because they are generally considered to be expressed in the former but not in the latter. However, we have encountered CK7+ and Cam 5.2+ SCCs.Methods
We evaluated CK7, Cam 5.2 and Ber-Ep4 expression in SCC and EPD.Results
We found significant CK7 and Cam 5.2 positivity in SCCs, particularly in those with a pagetoid pattern. Only one case expressed Ber-Ep4.Conclusions
We conclude that CK7 and Cam 5.2 expression may occur in SCC. A panel including Ber-Ep4 is advisable for immunohistochemical differentiation of EPD from SCC.