A small subset of both germinomas and NGGCTs (8.06%, 5/62, and 9.68%, 3/31, respectively) exhibited minimal T cell infiltration and low expression of immune checkpoints (CTLA-4, PD-1, and PD-L1); these NGGCTs were primarily teratomas or tumors with predominant teratoma components. Here, CTLA4 is linked to teratoma.