Abstract: Objective: To detect the level of PD-L1 in the patients with cutaneous squamous cell carcinoma (cSCC) and keratoacanthoma (KA), and to analyze the correlation between PD-L1 and the differentiation of cSCC. Methods: The expression level of PD-L1 in the lesions of cSCC and KA was detected by immunohistochemical staining. Results: Fifty-six patients with cSCC and 32 patients with KA were collected. The positivity rates of PD-L1 in cSCC patients were 66.07% and 62.50% in KA patients, which was significantly higher than that in controls (9.38%) (Ps<0.01). There was no significant difference in the positivity rate of PD-L1 between cSCC and KA patients (P>0.05). The level of PD-L1 was negatively correlated with the differentiation degree of cSCC (P<0.05). Conclusion: PD-L1 may not be a useful indicator for the differnece between cSCC and KA. The level of PD-L1 was negatively correlated with the differentiation degree of cSCC.

Key words: cutaneous squamous cell carcinoma, keratoacanthoma, programmed death factor ligand-1