Background  The aim of this study was to evaluate whether Fas (CD95) and Fas ligand (FasL) immunoreactivity in cutaneous squamous cell carcinoma (SCC) are correlated with grade of tumor differentiation.

Methods  A total of 31 cutaneous SCC specimens excised during 1997–2004 were collected from the four branch hospitals of the Catholic University of Korea. A tissue microarray technique was used for immunohistochemical staining. Expression of Fas and FasL was evaluated in correlation with the grade of tumor differentiation. Statistical analysis was performed using Fisher’s exact test and exact trend test.

Results  Six of 31 SCCs exhibited strong (+++) intensity for Fas immunostaining, and all of these were well differentiated. Five of 31 SCCs exhibited strong (+++) intensity for FasL staining; all of these were moderately or poorly differentiated.

Conclusions  Fas was expressed more strongly in well-differentiated SCCs than in poorly differentiated tumors. FasL was expressed more strongly in moderately and poorly differentiated tumors. These findings indicate that Fas and FasL play important roles in immune surveillance and grade of differentiation in SCC.