Extragonadal Germ Cell Tumors
A germ cell is a type of cell that forms as a fetus develops. These cells later become sperm in the testicles or eggs in the ovaries. Sometimes, germ cells may develop into a germ cell tumor in other parts of the body, either before or after birth.
Extragonadal germ cell tumors form in parts of the body other than the gonads (testicles and ovaries). They may begin to grow anywhere in the body, but usually form in the pineal gland in the brain, the chest, the lower part of the spine, or the abdomen.
Extragonadal germ cell tumors can be benign (noncancer) or malignant (cancer). Benign extragonadal germ cell tumors are called benign teratomas. These are more common than malignant extragonadal germ cell tumors and often are very large. The two types of malignant extragonadal germ cell tumors are nonseminomas and seminomas. Nonseminomas tend to grow and spread more quickly than seminomas. Nonseminomas are usually large and cause signs and symptoms.