CD274 and Epstein-Barr virus infection: It was reported that PD-L1 ligand expression was upregulated by EBV infection in cases of EBV-positive de novo CHL [32] and it has also been shown that LMP1 plays a significant role in PD-L1 expression [33,34]—not only in EBV-positive LPD but also in other cancers such as nasopharyngeal, gastric, and breast cancers [35,36,37,38].