Germ Cell Tumor

A germ cell tumor is a benign (noncancerous) or malignant (cancerous) mass that forms from germ cells. Most tumors appear in your ovaries or testicles, but they can occur in other body parts, too, including your chest, tailbone and brain. Germ cell tumors can affect anyone, but they’re most common in children, teens and young adults.


What is a germ cell tumor?

A germ cell tumor is a mass made of reproductive cells, also called germ cells. “Germ” is short for “germinate,” which means to mature. For women and people assigned female at birth (AFAB), germ cells eventually mature into eggs. For men and people assigned male at birth (AMAB), germ cells mature into sperm. Related, germ cell tumors most often form where eggs get made (ovaries) and where sperm gets made (testicles).

Less commonly, germ cell tumors form in body parts other than your ovaries and testicles, including your abdomen, chest, low back, tailbone and brain. These tumors are called extragonadal tumors.

Germ cell tumors most commonly affect children, teens and young adults.


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What are the types of germ cell tumors?

Germ cell tumors may be malignant (cancerous) or benign (noncancerous). Both types of tumors can grow larger, but only cancerous germ cell tumors can spread to other parts of your body. Cancer that’s spread (metastasized) can damage your organs and is more difficult to treat.

  • Teratomas are tumors that contain tissue like teeth, hair, muscle and bone. They may be mature or immature. Mature teratomas (dermoid cysts) are the most common type of ovarian germ cell tumor. They’re usually benign. Immature teratomas are typically cancerous, and they grow fast.
  • Yolk sac tumors (endodermal sinus tumors) contain cells similar to those in a developing embryo. These tumors are cancerous, and they spread fast to lymph nodes and other organs. Yolk sac tumors are the most common malignant germ cell tumor diagnosed in children.
  • Germinomas are cancerous tumors that may appear in your ovaries or testicles. Still, they’re most common in the brain and spinal cord (central nervous system). They’re called dysgerminoma when they’re in your ovaries and seminoma when they’re in your testicles.
  • Embryonal cell carcinoma is a rare, cancerous germ cell tumor. It may exist in a pure form, but it often appears alongside other tumor types in a mixed germ cell tumor.
  • Polyembryomas contain components that resemble embryos. They’re rare, fast-growing cancerous tumors often mixed with other types of germ cell tumors.
  • Choriocarcinomas consist of cells that form the placenta during pregnancy. The placenta is an organ that allows the gestational parent to share nutrients with a fetus. Choriocarcinoma is a rare and cancerous germ cell tumor that can form in your ovaries or testicles but often occurs in the uterus. It can spread to both the fetus and the parent.
  • Mixed germ cell tumors contain two or more types of malignant germ cell tumors. Many germ cell tumors are mixed.

What is the difference between seminomas and non-seminomatous germ cell tumors?

Germ cell tumors affecting men and people AMAB are classified as either seminomas or non-seminomas. Both are malignant tumors that may affect your testicles (testicular cancer).

  • Seminomas often grow and spread more slowly than non-seminomas.
  • Non-seminomas grow larger and spread more quickly than seminomas. Non-seminomas include yolk sac tumors, embryonal cell carcinomas, choriocarcinomas and teratomas.

How common are germ cell tumors?

Germ cell tumors in children are rare, making up only 3.5% of cancer diagnoses. They’re more common in adolescents and young adults, making up 13.9% of cancers diagnosed between ages 15 to 19.

Who is affected by germ cell tumors?

Anyone can have germ cell tumors, but infants, children, teens and young adults get them most often. Diagnoses increase and decrease based on age. For instance, diagnoses occur relatively frequently from infancy up to age 4 compared to the years immediately after. Germ cell tumor diagnoses increase as puberty approaches.

  • Ovarian germ cell tumors are most common in people aged 10 to 14, but they also affect people in their 20s and 30s. Mature teratomas, which are benign, are the most common germ cell tumor diagnosis.
  • Testicular germ cell tumors make up 75% of testicular cancer diagnoses in children and 90% of testicular cancers total. They’re more common in children younger than 4 and people ages 15 to 35.
  • Extragonadal germ cell tumors account for 40% to 50% of germ cell tumor diagnoses from infancy to age 4. Still, children and young adults get them, too. In infants and children, these tumors most commonly appear at the base of their spine (sacrum) or tailbone (coccyx). In teens and young adults, extragonadal germ cell tumors occur most often in the center of their chest (mediastinum). Brain germ cell tumors — although rare — are more commonly diagnosed in people between 11 and 30.

Symptoms and Causes

What are the symptoms of a germ cell tumor?

The symptoms of a germ cell tumor depend on factors like the tumor’s size and location in your body.

Ovarian germ cell tumors

Ovarian germ cell tumors don’t always cause symptoms. For instance, mature teratomas may not cause symptoms until they’ve grown large enough to create pressure in your abdomen. Often, they’re discovered on an ultrasound to determine what’s causing pelvic pain.

Symptoms may include:

Testicular germ cell tumors

The symptoms of testicular germ cell tumors are the same as those of testicular cancer.

Symptoms include:

  • Solid, firm lump in a testicle that grows bigger (with or without pain).
  • Pain or heaviness in your scrotum.
  • Abdominal pain or groin pain.
  • Oddly shaped testicle.
  • Back pain.

Extragonadal germ cell tumors

A mass on your child’s tailbone or in the center of their chest may signify a teratoma. Other symptoms of an extragonadal germ cell tumor depend on the tumor’s location.

  • Trouble breathing (lungs).
  • Weakness in legs (low back).
  • Trouble peeing and pooping (pelvis).
  • Swelling and acute or dull pain in your child’s belly.

Some germ cell tumors secrete reproductive hormones that may cause symptoms of early puberty or atypical sexual development in children. People AFAB may develop breasts, grow pubic hair and get their periods early. People AMAB may grow breasts (gynecomastia).

What causes a germ cell tumor?

Normal germ cells form in a developing human embryo. These cells eventually travel to the embryo’s ovaries or testicles, becoming egg cells or sperm cells.

In contrast, germ cell tumors consist of cells that don’t develop into fully formed eggs or sperm. The germ cells divide abnormally and become a tumor in your ovaries or testicles instead. In the case of extragonadal tumors, the germ cells travel to odd places in your body — like your chest, brain, belly, low back and tailbone — to form tumors.

Researchers aren’t sure what causes germ cells to develop this way.

What are the risk factors associated with germ cell tumors?

You may be more likely to get a germ cell tumor if you have a family history of germ cell tumors or a history of certain conditions.

These include:

Diagnosis and Tests

How are germ cell tumors diagnosed?

Your healthcare provider will perform a physical exam and ask about symptoms. They may perform any of the following tests or procedures to diagnose a germ cell tumor:

  • CT scan: A CT scan combines multiple X-ray images of the inside of your body to create a computerized, 3D image of your bones and soft tissues. A CT scan of your chest, abdomen or pelvis can show a tumor’s location.
  • MRI: An MRI uses magnets and radio waves to create a computerized image of bone and soft tissue in your body. Like a CT scan, an MRI can show your tumor’s location.
  • Ultrasound: An ultrasound uses sound waves to create images of the inside of your body. Ultrasounds show how much of a tumor is a solid mass or cystic (filled with fluid). This information can be helpful when determining whether a growth is a germ cell tumor or a cyst.
  • PET scan: A PET scan uses a tracer that can show where cancer cells are in your body. A PET scan can show if cancer has spread.
  • Bone scans: A bone scan takes X-rays of your bones after they’ve absorbed a special dye that makes abnormalities stand out. Bone scans can show if a tumor is affecting your bones.
  • Blood tests: Your provider may do a blood draw to check the amounts of enzymes, proteins or hormones in your blood. Elevated levels of human chorionic gonadotropin (hCG), a-fetoprotein (AFP) and lactate dehydrogenase may indicate certain kinds of germ cell tumors.
  • Biopsy: A biopsy removes tissue from the tumor and sends it to a lab for testing. A specialist called a pathologist analyzes the sample underneath a microscope to diagnose a germ cell tumor.

Your provider may remove the affected organ if your tumor’s likely malignant. For instance, removing your entire testicle (radical inguinal orchiectomy) is a standard part of a testicular cancer diagnosis. Removing your testicle allows your provider to analyze the tissue and provide treatment (surgery).

Management and Treatment

How are germ cells treated?

  • Surgery: Surgery is the primary treatment for germ cell tumors. Your provider may remove the tumor from the affected ovary (ovarian cystectomy) or the entire ovary and fallopian tubes (salpingo-oophorectomy). With testicular cancer, your provider will remove the testicle with the tumor.
  • Chemotherapy: Chemotherapy uses drugs to destroy cancer cells or prevent them from dividing. You might receive chemotherapy if your provider can’t remove the tumor safely or if it has spread to other parts of your body. You may receive chemotherapy to destroy any remaining cancer cells following surgery, even if you can’t see the cancer cells on imaging. Chemotherapy is an effective treatment for most types of germ cell tumors.
  • Radiation therapy: Radiation therapy directs high-energy X-rays to cancer cells to destroy them. Some types of germ cell tumors respond best to radiation therapy.

Outlook / Prognosis

Is a germ cell tumor curable?

The prognosis for most germ cell tumors is excellent. Removing the tumor completely often cures the disease. For instance, testicular cancer has a 95% survival rate following treatment. Ovarian germ cell tumors have a 93% survival rate. The cure rate for children with germ cell tumors ranges from 82% to 90%.

Still, likely outcomes depend on various factors unique to you, including:

  • Your age.
  • The type of germ cell tumor.
  • The tumor’s location and size.
  • Where the cancer’s spread.
  • How the tumor responds to treatment.

Talk to your healthcare provider about how your diagnosis will affect your outcomes.

Living With

What questions should I ask my doctor?

Questions that you can ask to better understand your diagnosis include:

  • Is my tumor malignant (cancerous)?
  • How aggressive (fast-growing) is my tumor?
  • Has the cancer spread?
  • What treatments would you recommend?
  • What are potential treatment side effects?
  • What are the likely outcomes associated with each treatment option?
  • What tests will I need to monitor the effectiveness of the treatment?
  • How often will I need follow-up visits to monitor my tumor/response to treatment?

A note from Cleveland Clinic

A germ cell tumor is a mass made of reproductive cells, also called germ cells. Your healthcare provider can explain what a germ cell tumor diagnosis means for you or your child. Germ cell tumors are complex. The symptoms you experience and your likely prognosis all depend on various factors that your provider can discuss with you. Luckily, most germ cell tumors respond well to treatment. As with any other tumor diagnosis (especially malignant tumors), the earlier you’re diagnosed and begin treatment, the better your outcome will likely be.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 07/15/2022.

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