In a fetus, germ cells are cells that should become sperm in the testicles or eggs in the ovaries. Sometimes these cells don’t travel to the right part of the body and end up forming a tumor. These tumors can be either benign or malignant, meaning they can spread to other parts of the body. Malignant tumors are cancer.
One way to classify germ cell tumors is based on where they form. Most malignant germ cell tumors are gonadal, meaning they’re in either the ovaries or testes. They can also form in the brain’s pineal gland, near the pituitary gland. Other places they form include the:
- Coccyx, or tailbone
- Mediastinum, the area between the lungs
- Sacrum, a large bone in the lower spine that forms part of the pelvis
Germ cell tumors are also defined by how they look under a microscope and/or the hormones they produce.
Teratomas are usually benign, but some are malignant. Teratomas of the tail bone are the most common germ cell tumor found in children, and are about four times more common in girls than in boys.
Germinomas make the beta-human chorionic gonadotropin hormone. Those that form in the ovaries are called dysgerminomas, while ones in the testes are seminomas. They can also appear outside the ovaries or testes. In these cases, they’re simply called germinomas.
- Yolk sac tumors, also known as endodermal sinus tumors. They can form in the ovaries, testes or other parts of the body. They are the most common type of testicular cancer in infants and children.
- Embryonal carcinoma. These are malignant and most commonly found in the testicles, but can spread to other parts of the body.
- Gonadoblastomas, which are rare, almost always benign tumors associated with abnormal development of the reproductive organs.
- Polyembryomas. They are a very rare, aggressive type of germ cell tumor that is usually found in the ovaries.
Childhood germ cell tumors risk factors
There are several factors that seem to increase the risk of a child developing a germ cell tumor.
Certain genetic conditions are tied to increased risk for specific types of germ cell tumors:
- Klinefelter syndrome may increase a person’s chances of developing a tumor in the mediastinum, the area between the lungs.
- Swyer syndrome may increase a person’s chance of developing a germ cell tumor in the ovaries or testicles.
- Turner syndrome may increase the risk of ovarian germ cell tumors.
In addition, having an undescended testicle increases the odds of a male developing a testicular germ cell tumor.
A family history of germ cell tumors also increases the chance that someone will develop a germ cell tumor.
In rare cases, childhood germ cell tumors can be passed down from one generation to the next. Genetic counseling may be right for you. Visit our genetic testing page to learn more.