DNTT and extragonadal germinoma: For example, one study reported that terminal deoxynucleotide transferase (TdT) can be used as a new IHC marker for the diagnosis of various extragonadal GCTs with a high positive rate in seminomas (99%, 107/108), ECs (100%, 15/15), and extragonadal germinomas (100%, 11/11) and absence in YSTs (0/38) and teratomas (0/19) (60).