CD8A and primitive neuroectodermal tumor: Levels of CD3+ and CD8+ T cell infiltration in the primary sites of both the localized and metastatic PNET groups were analyzed by classifying infiltration levels into 3 groups (mild [<5%], moderate [5%–50%], and diffuse [>50%]) following guideline recommendations by evaluating the whole tumor area on a single section (Figure 4) (35, 36).