A teratoma is a rare type of germ cell tumor that may contain immature or fully formed tissue, including teeth, hair, bone and muscle. Most teratomas are benign (noncancerous) but they can be malignant (cancerous). Treatment involves surgical removal. Cancerous teratomas may require chemotherapy, radiation therapy or other cancer treatments.


What is a teratoma?

A teratoma is a type of germ cell tumor — a tumor that starts in your reproductive cells like eggs and sperm. Most teratomas are benign (noncancerous), but sometimes they can become malignant (cancerous).

Germ cells are the only cells in your body that can turn into many other types of cells. So, when a tumor starts in your germ cells, it can turn into many different types of tissue. This means teratomas can contain fragments of any body part. Some of the most common structures inside a teratoma include:

Less commonly, teratomas can even contain remnants of complex body parts like:

It’s even possible to have one with eyes — at least parts of them, including eyeballs. But to date, there’s no record of a teratoma with complete body organs.

Types of teratomas

Healthcare providers categorize teratomas into two main types:

  • Mature teratomas are usually noncancerous (benign tumors). Mature teratomas can occur at any age, but they’re most common during your reproductive years.
  • Immature teratomas are cancerous. They’re most common among children.

Teratomas can form anywhere in your body. Some examples include:

  • Ovarian teratomas. These are the most common type in women and people assigned female at birth (AFAB). Most ovarian teratomas are cystic teratomas (filled with fluid, tissue or other materials). A very small percentage of them are cancerous. Most are benign.
  • Testicular teratomas. These are the most common type in men and people assigned male at birth (AMAB). In children, these tumors are usually noncancerous. But in the adult population, they’re malignant in over half of the cases.
  • Sacrococcygeal teratomas. These are the most common type in children. But they’re still rare overall, occurring in about 1 in 40,000 live births. This tumor develops near the coccyx (tailbone) and is more common among people AFAB.
Fetiform teratomas

The rarest type of teratoma tumor, a fetiform teratoma occurs in about 1 out of every 500,000 people. It’s a type of dermoid cyst that consists of living tissue and often resembles a malformed fetus. But because there’s no placenta or amniotic sac, the fetus has no chance of development. In about 90% of cases, healthcare providers diagnose fetiform teratomas within the first 18 months of life.

A fetiform teratoma resembles a parasitic twin (fetus in fetu). Fetus in fetu only occurs in twins who both share the same placenta and have their own sac of amniotic fluid.


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Symptoms and Causes

What are the symptoms of a teratoma?

People with teratomas may not show any symptoms at first. Once symptoms develop, they can vary significantly depending on the tumor’s location. General teratoma symptoms may include:

  • Pain.
  • Bleeding.
  • Swelling.
  • Slightly elevated levels of the hormone BhCG (beta-human chorionic gonadotropin).
  • Slightly elevated levels of tumor marker AFP (alpha-fetoprotein).

But you may also develop specific additional symptoms based on the location of the teratoma tumor.

Ovarian teratoma symptoms

Main symptoms of ovarian teratomas include:

In some instances, ovarian teratomas may occur alongside NMDA encephalitis — a rare condition that can lead to severe headachesconfusion and psychosis.

Testicular teratoma symptoms

Primary symptoms of testicular teratomas include:

  • Lump in your testicle.
  • Swelling in one or both testicles.

In some cases, people with testicular teratomas may not show any symptoms.

Sacrococcygeal teratoma symptoms

Sacrococcygeal teratomas can form inside or outside your body in the tailbone (coccyx) area. Possible symptoms include:

What causes a teratoma?

A teratoma develops when there are disruptions during your cells’ differentiation process. It’s sort of like cell differentiation in an embryo: Unspecialized cells (cells that don’t have a specific function yet) turn into specialized cells with a specific purpose (like blood cells, nerve cells and muscle cells).

In the case of a teratoma, your unspecialized germ cells turn into different types of specialized cells (like hair cells, muscle cells and bone cells). That’s why a teratoma contains a collection of seemingly random body parts and tissues.


What are the complications of a teratoma?

Specific complications vary based on the location of the teratoma. But in general, teratoma complications may include:

  • Torsion (a body part twists and causes pain).
  • Rupture (a tumor bursts or breaks open).
  • Infection.
  • Cancerous transformation (a tumor that started as noncancerous turns cancerous).

Diagnosis and Tests

How do healthcare providers diagnose teratomas?

A healthcare provider will do a physical examination and ask about your symptoms and medical history. They may also recommend tests to confirm a diagnosis.

These tests may include:

With the development of imaging technology, healthcare providers can sometimes diagnose a teratoma during pregnancy.


Management and Treatment

How do healthcare providers treat teratomas?

Typically, the first step is surgery to remove the teratoma. Nearly all teratomas require removal when discovered. Even if they aren’t cancerous, they can still grow or rupture, leading to other issues.

If your teratoma is cancerous, your healthcare provider may also recommend:


How do you prevent teratomas?

Currently, there’s no known way to prevent teratomas. But early treatment can greatly reduce your risk for complications.

Outlook / Prognosis

What’s the outlook for someone with a teratoma?

The vast majority of teratomas are noncancerous. In most cases, these tumors don’t spread like aggressive cancers. As a result, most teratomas — even cancerous ones — have excellent survival rates with early diagnosis and treatment.

Living With

When should I call my healthcare provider?

Anytime you notice a new lump or bump on your skin or persistent abdominal pain, you should schedule a visit with a healthcare provider. They can run appropriate tests and give you a diagnosis.

If you already know you have a teratoma, or had surgery to remove one, you should call your provider if you develop pain or other new symptoms.

Additional Common Questions

Can you have a teratoma on your face?

Facial teratomas are possible, but rare. Head and neck teratoma tumors make up less than 6% of all teratomas.

Why do teratomas have teeth and hair?

Teratomas often contain teeth, hair and other tissues because they form in your germ cells. Germ cells can turn into any type of tissue.

Can a teratoma have a heartbeat?

It’s rare, but some teratomas can produce a “heartbeat” of sorts. Teratomas that develop into cardiac tissue can sometimes show heartbeat-like pumping activity.

What if my provider finds a teratoma on the fetus during pregnancy?

If your provider finds a teratoma during the fetal stage of development, they’ll monitor your pregnancy closely. Small teratomas usually aren’t threatening and shouldn’t disrupt delivery. Large teratomas may require early delivery via C-section. Rarely, you may need fetal surgery to remove the teratoma before it leads to serious complications.

Before planning your treatment, your healthcare provider will take your unique situation into account. Treatment will depend on several factors, including your age, medical history, overall health and personal preferences.

A note from Cleveland Clinic

Teratomas might sound like something out of a sci-fi movie. But they’re really just a result of germ cells going rogue. Teratomas are rare, so finding out you have one can feel scary. They usually aren’t cancerous, but they can cause complications if they grow or rupture. If you have a teratoma, the best thing you can do is follow your healthcare provider’s recommendations. This usually means having surgery to remove the tumor. With prompt treatment, your outlook is positive.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 09/19/2023.

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