CD274 and melanoma: PD-L1 expression was significantly correlated with melanoma localizations in infiltrating immune cells (X2 = 9.603, p = 0.018) and Breslow tumor thickness in melanoma tumor cells (X2 = 9.933, p = 0.014), but no significant relationship between PD-L1 expression and age, gender, or morphological characteristics was seen (Clark level of invasion, lymphovascular invasion, and perineural invasion).