Extracranial germ cell tumors are growths caused by immature cells that normally would have developed into mature eggs (in a female) or sperm (in a male). Although these tumors are rare in children under the age of 15, they are the most common solid tumors in adolescents, accounting for about 14% of all cancers among those aged 15 to 19.

These tumors can be noncancerous (benign) or cancerous (malignant), and may appear in many areas of the body, including:

• Testicles or ovaries
• Tailbone 
• Chest 
• Abdomen
• Head and neck

At Children’s Hospital of Philadelphia (CHOP), our team specializes in diagnosing and caring for children and teens with these uncommon tumors. We partner closely with patients and their families to make sure they understand each step of their healing journey, helping them to choose the most effective treatment option.

What are extracranial germ cell tumors?

Germ cells develop early in pregnancy and typically travel to the baby’s developing ovaries or testicles. Sometimes these cells settle in other parts of the body instead. This can cause extracranial germ cell tumors to form.

There are many types of extracranial germ cell tumors.

• Mature teratomas
  • Usually noncancerous
  • Cells closely resemble normal tissue
• Immature teratomas
  • Usually noncancerous
  • May contain less developed tissue
• Malignant germ cell tumors
  • May grow and spread quickly
  • Require prompt treatment
  • Types include:
    • Yolk sac tumors
    • Germinomas
    • Embryonal carcinomas
    • Choriocarcinomas
• Mixed germ cell tumors
  • Contain more than one cell type

These tumors are also grouped by location on the body.

• Gonadal tumors
  • Tumors that start in the testicles or ovaries
• Extragonadal tumors
  • Tumors that develop outside the reproductive organs

Extracranial germ cell tumors are rare, making up about 3% of childhood cancers. They occur most often in teens, though some types — especially teratomas — appear more often in infants and young children.

What are the causes of extracranial germ cell tumors?

For most children, the reason for extracranial germ cell tumor formation is unknown.

Research shows that certain inherited genetic conditions – such as Klinefelter syndrome, gonadal dysgenesis and Turner syndrome – may increase the risk of extracranial germ cell tumor formation, although these instances are uncommon. An undescended testicle can increase risk for gonadal germ cell tumor formation.

When extracranial germ cell tumors form, it is important to remember that neither parent did anything to cause it.

What are the signs and symptoms of extracranial germ cell tumors?

Your child may show different symptoms depending on where the tumor forms on the body, as well as the type of tumor. In many cases, children show signs related to pressure or swelling in the affected area.

Common symptoms of extracranial germ cell tumors in children and adolescents include:

• A visible lump or swelling (often in the groin, abdomen, chest or tailbone)
• Pain or discomfort
• Changes in bowel or bladder habits
• Breathing difficulty
• Early or delayed puberty

Cancerous tumors may also cause:

• Fatigue
• Poor appetite
• Weight loss

Any new, unexplained lump or persistent symptom should be evaluated by a healthcare professional, like your child’s pediatrician, immediately.

How do you test and diagnose extracranial germ cell tumors?

Diagnosing an extracranial germ cell tumor usually involves several steps.

• Medical history and physical exam
  • A specialist reviews your child’s symptoms and examines the area where the tumor may be present.
• Blood tests
  • Doctors check for tumor markers released into the blood by certain types of germ cell tumors. These markers help in both diagnosing and monitoring treatment.
    • Alpha‑fetoprotein (AFP): Often elevated in yolk sac tumors
    • Beta‑human chorionic gonadotropin (β‑hCG): Elevated in some germinomas or choriocarcinomas
• Imaging
  • These help determine the size and location of the tumor and whether it has spread. This might include tests such as:
    • Ultrasound
    • MRI
    • CT scans
• Biopsy
  • In many cases, a sample of tissue is taken to confirm the type of tumor.

What are the treatment options for extracranial germ cell tumors?

At CHOP, treatment for extracranial germ cell tumors is tailored to your child’s age, as well as tumor type and location. 

• Surgery
  • Many noncancerous teratomas can be removed surgically. Surgery may also be used to remove cancerous tumors when possible.
• Chemotherapy
  • Chemotherapy is very effective for many children and teens. It is used to treat cancerous germ cell tumors, especially if they have spread or cannot be fully removed by surgery.
  • High-dose chemotherapy with (auto) stem cell transplant may be a treatment option for disease that is difficult to treat or comes back. 

Children and adolescents treated for extracranial germ cell tumors maybe also receive additional support, including:

• Fertility counseling 
• Physical therapy
• Psychosocial support

CHOP’s pediatric cancer team is made up of internationally known oncologists and surgical oncologists with expertise in every type of cancer, ready to partner with patients and their families to create unique, specialized treatment plans.

What is the long-term outlook for children with extracranial germ cell tumors?

Outcomes for children with extracranial germ cell tumors depend on several factors, including tumor type, whether it is cancerous and if it has spread. 

Many children — especially those with tumors found early — respond very well to treatment.

What follow‑up care is needed for children treated for extracranial germ cell tumors?

CHOP’s care team creates personalized follow‑up plans based on the unique needs of each patient. 

Regular follow‑ups are important for any child or teen treated for extracranial germ cell tumors, allowing doctors to:

• Monitor for tumor recurrence
• Track tumor marker levels
• Support long‑term health after treatment

At CHOP, our childhood cancer experts will be by your side through every step of your child’s healing journey.