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What Are Germ Cells?

Germ cells are the reproductive cells in an unborn baby. In boys, the cells make sperm and in girls, they make eggs.

Before they settle into the reproductive organs, germ cells develop along the baby's "midline." This is the area where the stomach and other internal organs will lie.

What Are Germ Cell Tumors?

Germ cells that grow in an unusual way can become a . Often, these tumors form in the ovaries or testes. Because the germ cells travel along the midline to reach the reproductive organs as a fetus grows, they can sometimes settle in other places.

The most common sites for germ cell tumors outside of the reproductive organs are:

  • in part of the chest between the breastplate and spine
  • the tailbone
  • abdomen (belly)
  • pelvis

Sometimes, a tumor can develop in the middle part of the brain.

What Are the Types of Germ Cell Tumors?

Like tumors that form in other places in the body, germ cell tumors can be (not cancerous) or malignant (cancerous). The most common types of germ cell tumors include:

Teratomas. These tumors are benign, but can become malignant. Teratomas are the most common type of germ cell tumor to develop in extragonadal (not in the ovary or testes) areas. Doctors usually treat teratomas with surgery because chemotherapy doesn't work in a benign tumor.

Germinomas. These malignant tumors are also called dysgerminomas when they're in the ovary, or seminomas when they're in the testes. They also can be in the middle part of the brain.

Yolk sac tumor (also called endodermal sinus tumor). These malignant tumors most often develop in the ovaries, testes, or tailbone.

Embryonal carcinoma. These malignant tumors usually form in the testicle of an adolescent boy, but can spread ( ) to other places in the body.

Choriocarcinoma. This malignant tumor usually forms in the placenta during pregnancy and can affect both the mother and child.


What Causes Germ Cell Tumors?

The cause of most germ cell tumors isn't always known. Doctors do know that some medical conditions can make children more likely to develop them. These include:

  • birth defects that involve the central nervous system, genitals, urinary tract, and spine
  • genetic conditions that cause missing or extra sex

Boys with undescended testicles (testes that stay up inside the pelvis) also seem to be at a higher risk for a germ cell tumor.

What Are the Signs & Symptoms of Germ Cell Tumors?

Early on, a child with a benign or malignant germ cell tumor might have few symptoms or none at all. As the tumor grows, a mass (lump) may be felt. It also might cause symptoms as it presses against organs in the body.

Depending on where the tumor is, it can cause symptoms like:

  • constipation or trouble holding pee if the tumor is in the pelvis
  • leg weakness if the tumor presses on the nerves at the bottom of the spine
  • a testicle of an unusual shape or size

How Are Germ Cell Tumors Diagnosed?

If a doctor thinks that a child might have a tumor, he or she will do a physical exam and order these tests:

Imaging studies. These might include a CT scan, MRI, X-ray, ultrasound, and a bone scan. These tests help doctors see the size of the tumor and where it is. They can also help show if cancer has spread to other parts of the body.

Biopsy. In a biopsy, doctors take a small piece of tissue for examination in a lab. This closer look by a helps the (cancer doctor) make a diagnosis and choose the right treatment. Biopsies often can be done through a laparoscope using a small incision (cut) and a camera to guide the doctor. A more complicated surgery might be needed based on the tumor's location.

Blood tests. Tests such as a blood count, kidney test, and liver test measure minerals in the blood. The results show how well the liver and other organs are working. Alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (β-HCG) tests look for higher than normal levels of these proteins (called tumor markers). Higher levels can suggest a germ cell tumor. These tests also can show how the cancer treatment is working and, after treatment, whether the tumor has come back.

Doctors might order genetic tests if a tumor could be related to a genetic condition.

How Are Germ Cell Tumors Treated?

Children with benign germ cell tumors will have surgery to remove the tumor. Those with malignant tumors will first go through a process called staging.

Staging is a classification system that helps doctors figure out how far the cancer has progressed. It looks at things like:

  • the size of the tumor (or tumors)
  • how deep the tumor is in an organ
  • whether the tumor has spread to nearby or distant lymph nodes or organs

This information, as well as a child's age and overall health, helps doctors form treatment plans. The plans may include these options, used together or alone:

Surgery. Children with malignant tumors may have surgery to remove as many of the cancerous cells as possible.

Chemotherapy. Chemotherapy works to treat cancer throughout the body. Chemo is also the most important therapy to treat microscopic (very tiny) cells that can hide in other parts of the body but aren't seen on a scan or felt on exam. Often, doctors combine several chemotherapy drugs to attack the cancer cells in different ways.

Radiation therapy. This treatment uses high-energy radiation from X-rays, gamma rays, or fast-moving subatomic particles (called particle or proton beam therapy) to target and destroy cancer cells. Radiation usually isn't needed to treat germ cell tumors because most are very sensitive to chemotherapy.

Looking Ahead

When your child needs treatment for any type of tumor, it can feel overwhelming. But you're not alone. To find support, talk to your child's doctor or a hospital social worker. Many resources are available to help you and your child get through this difficult time.

Medically reviewed by: Howard M. Katzenstein, MD
Date reviewed: June 2018