Although it has been claimed that invasive cutaneous squamous cell carcinoma (SCC) does not express CD10, very few examples have been investigated regarding this matter. The claim of our study is to investigate the expression in 20 cases of SCC of different grades of differentiation. For that, we randomly selected from our archives 5 SCC-keratoacanthomatous (KA)-type; 5 SCC non-KA, well-differentiated; 5 SCC, moderately differentiated; and 5 SCC, poorly differentiated. In all these cases, we performed an immunohistochemical study for CD10. We found expression of CD10 (either stromal or cytoplasmic) in all the cases. While stromal expression (either focal or diffuse) seemed to have no relation to the degree of differentiation of the tumor, cytoplasmic expression of the marker was not found in any of the cases of the poorly-differentiated group. We conclude that 1) stromal expression of CD10 is not lost in deeply invasive SCC, as previous literature has suggested; 2) lack of cytoplasmic expression of CD10 by cutaneous SCC can be considered as an additional prognosis factor to investigate in the future; 3) our results seem contradictory to the current view that has defended atypical fibroxanthoma as an anaplastic type of SCC, since the former expresses CD10 in virtually 100 % of the cases.

Service of Anatomic Pathology Hospital El Bierzo Spain