What are germ cell tumors?

Germ cells are the cells that make sperm and eggs. They are part of our reproductive system. If germ cells start to grow out of control, they can form germ cell tumors.

These cells start forming while the fetus is still growing in the mother’s womb. Germ cells move toward the site where the child’s sex glands — the testicles or ovaries — will form. These glands are also called the gonads.

In most cases, childhood germ cell tumors form in the gonads. But some germ cells do not make it as far as the gonads when they move. Instead they stop somewhere else in the body. So germ cell tumors can form in other places, such as near the gonads, in the belly, in the space between the breastbone and spine (mediastinum) and in the brain. Germ cell tumors outside the gonads are called extragonadal.

Germ cell tumors can be cancerous (malignant) or not cancerous (benign). Most are not cancer. Benign germ cell tumors can still cause health problems, however, because they may be large and press on other structures. They need treatment.

Germ cell tumors that are cancer include:

  • Yolk sac tumor
  • Choriocarcinoma
  • Seminoma or germinoma

Germ Cell Tumors in Children

Germ cell tumors in children are rare. Among all children under age 15 who have cancer, only about 1% have germ cell tumors.

Doctors do not know what causes them.

Germ Cell Tumor Stages

Children who have a germ cell tumor (malignant or benign) are considered to be at one of these stages:

Stage 1

Doctors were able to remove the whole tumor through surgery, and tumor markers do not suggest any more tumor activity.

Stage 2

After doctors remove the tumor, they know or suspect some tumor cells were left behind. Tumor markers may suggest the tumor is still active.

Stage 3

Doctors can still see parts of the tumor in the child's body after treatment. Also, there are tumor cells in the lymph nodes.

Stage 4

Doctors find tumor cells have spread to other sites in the body outside the area near the tumor.

Germ Cell Tumors at Seattle Children's

At Seattle Children’s, our doctors and other members of your child’s team have worked with many children with germ cell tumors. It’s important to work with doctors who have experience treating this rare condition. We can offer the latest treatments for your child.

Germ cell tumor treatment sometimes starts in our Prenatal Diagnosis and Treatment Program. If doctors detect a germ cell tumor before a baby is born, our Prenatal Team helps families and their obstetricians get ready for the birth and plan for tumor treatment.

Read more about expert treatment and outcomes for germ cell tumors at Seattle Children’s.

Contact Us

If you have questions about germ cell tumor treatment, call: