Germ cell tumor (GCT) is a tumor (neoplasm) derived from germ cells.
In females, germ cell tumours account for 30% of ovarian tumours, but only 1 to 3% of ovarian cancers in North America. In younger women germ cell lesions are more common, thus in patients under the age of 21, 60% of ovarian tumours are of the germ cell type, and up to one-third are malignant. In males, germ cell tumours occur typically after puberty and are malignant (testicular cancer).
Germ cell tumors may develop outside of the gonads. Most germ cell tumors (both benign and malignant) diagnosed in neonates, infants, and children younger than 4 years are sacrococcygeal teratomas.