Expression of UTF1 in primary and metastatic testicular germ cell tumors.

We immunohistochemically evaluated UTF1 in 104 primary and 68 metastatic testicular germ cell tumors and 339 non-germ cell tumors. The percentage of tumor cells stained was semiquantitatively scored (0, no tumor cell staining; 1+, ≤30% of cells; 2+, 31%-60% of cells; 3+, 61%-90% of cells; 4+, >90% of cells). Staining intensity (nuclear) was scored as weak, moderate, or strong. UTF1 staining was seen in all 56 intratubular germ cell neoplasias, unclassified type (2+, 1; 3+, 2; 4+, 53; weak, 4; moderate, 49; strong, 3), all 72 seminomas (1+, 2; 2+, 4; 3+, 8; 4+, 58; weak, 10; moderate, 33; strong, 29), and 59 embryonal carcinomas (3+, 2; 4+, 57; moderate, 1; strong, 58). Weak UTF1 staining was seen in 15 of 37 yolk sac tumors (1+, 10; 2+, 2; 3+, 2; 4+, 1). All 34 teratomas, 9 choriocarcinomas, and 6 spermatocytic seminomas were negative for UTF1 staining. Among the 339 non-germ cell tumors, only 18 showed weak UTF1 staining (1+ to 4+). Normal prepubertal and postpubertal spermatogonia showed weak to strong UTF1 staining. UTF1 was differentially expressed in testicular germ cell tumors. Strong UTF1 staining can be used for diagnosing embryonal carcinoma and seminoma. UTF1 expression in spermatogonia suggests its possible role in spermatogenesis and renewal of spermatogonia.