CTLA4 and yolk sac tumor: Characterization of the immune infiltrate in terms of immune checkpoint PD-L1/CTLA-4 expression and its correlation with patient outcome was carried out by Lobo et al. A predominant portion of 162 analyzed samples exhibited PD-L1 and CTLA-4 positivity in infiltrating immune cells (ICs) regardless of the histological subtype, while the expression of CTLA-4 in tumor cells (TCs) was significantly higher in yolk sac tumor, choriocarcinoma, and teratoma samples.