Kwon MJ, et al. - Experts exploratively assessed the clinicopathological features, prognostic value, and co-expressed molecules of programmed death-ligand 1 (PD-L1) in tonsillar squamous cell carcinomas (TSCCs). During this research, PD-L1 expression was evaluated by immunohistochemistry using a specific monoclonal antibody (SP142) between whole tissue and tissue microarray (TMA) sections of 79 tumors. It was determined that PD-L1 positivity was a favorable independent prognostic factor. Subgroup analyses based on the co-expression of PD-L1 with human papillomavirus (HPV), SNIP1, or unmethylated TWIST1 revealed the best clinical outcome compared to any other subgroups. The occurrence of intratumoral heterogeneity of PD-L1 expression appeared to be frequent, requiring a caution in punching TMA cores. A characteristic subset of patients and prognostic group could be defined via combined analysis of PD-L1 with epithelial-to-mesenchymal transition and HPV.