PDCD1 and cancer: In our study, we observed higher PD-L1 expression in VSCCs, with 86.2% in ICs and 82.4% in peritumoral cells within the tumor microenvironment, suggesting that the PD-1/PD-L1 pathway may be more crucial in VSCC carcinogenesis compared to other cancer sites [47,48,52,53,54].