POU5F1 and testicular germ cell tumor: Previously, it was reported that 5.7% of patients with CO express the proteins POU5F1, PLAP, SALL4, AP2γ, and KIT, which are associated with the risk of developing GCNIS, the precursor lesion of TGCT [6,23,28], This is consistent with our results, indicating that 16.7% of the CO patients had these characteristics.