A teratoma is a rare type of germ cell tumor (GCT) containing different types of tissue, such as hair, bone, teeth, and muscle. They most commonly affect the ovaries, testicles, and tailbone but can occur elsewhere in the body. Some are cancerous.

Teratomas are a type of GCT. This term refers to a tumor that develops from germ cells, which are the cells that develop into the cells that make up the male and female reproductive systems. This is why teratomas commonly occur in the testes and ovaries. However, germ cells can migrate to other parts of the body and develop into tumors known as extragonadal germ cell tumors.

Teratomas can appear in newborns, children, or adults. They may be benign, meaning noncancerous, or malignant. The treatment plan for a teratoma will typically involve surgery.

In this article, we discuss teratomas in more detail, including the symptoms, causes, diagnosis, and treatment of this type of tumor.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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A teratoma is a type of tumor that may contain many different tissues. Its name comes from the Greek for “monstrous tumor.” For example, it may contain:

  • hair
  • bone
  • teeth
  • muscle
  • organs

These types of tumors often develop in the gonads, which is why the testicles and ovaries are common sites. However, they can occur elsewhere in the body, especially in midline locations. These are sites in the middle of the body, such as the head and spine. Common sites for teratomas can include:

Doctors typically classify teratomas into two subtypes: mature or immature. An immature teratoma looks very different than normal cells under a microscope and is usually malignant. In contrast, mature teratomas appear similar to normal cells and are usually benign. Both types may produce enzymes or hormones that can cause signs and symptoms of disease.

The symptoms of a teratoma can vary depending on the size and location of the tumor. In some cases, people with teratomas may not have any symptoms at all and only notice a mass when it becomes large enough to be noticeable.

Possible symptoms include:

  • a mass, swelling, or lump that a person can feel or see
  • constipation or incontinence
  • leg weakness
  • abdominal pain
  • difficulty breathing

If a teratoma is hormone-secreting, it may cause noticeable symptoms in prepubescent children and can result in precocious puberty, which is the very early onset of puberty. These hormonal changes can occur in male or female children.

At present, the exact cause of teratomas is unknown. However, they may have a link with inherited conditions that affect the central nervous system, genitourinary tract, and lower spine.

Research suggests that teratomas occur due to changes in embryonic stem cells. These special cells are pluripotent, which means they are able to develop into any other cell in the body.

During development, some of these cells may not differentiate, instead retaining the ability to turn into other cell types. This is why teratomas may feature many different body parts, such as bone, hair, or teeth, which are foreign to the location of the tumor.

Risk factors may also vary depending on the type of teratoma. For example, research suggests that risk factors for testicular teratomas can include:

  • low birth weight and small size at birth
  • cryptorchidism
  • hypospadias
  • maternal bleeding
  • advanced maternal age
  • jaundice
  • retained placenta

Risk factors for ovarian teratomas becoming malignant may include:

  • older age
  • large tumor size
  • having gone through menopause
  • elevated levels of a protein called cancer antigen 125 (CA-125)

In addition to taking a medical history and doing a physical exam, a doctor will likely use the following tests to help diagnose a teratoma:

  • imaging, such as a CT scan or ultrasound, to locate a potential tumor
  • alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG) blood tests, with elevated levels indicating the presence of a teratoma
  • complete blood count (CBC)
  • liver, kidney, and lung function tests
  • a biopsy of the mass

Doctors may also accidentally discover a teratoma while performing tests to diagnose another illness or condition.

After reaching a diagnosis, a doctor will also stage the cancer from 1 to 4. This classification refers to the size of the tumor and whether it has spread to other parts of the body. A stage 1 teratoma will be small and localized, but by stage 4, it will be larger and have spread to distant locations.

In most cases, treatment for a teratoma will involve surgically removing the entire tumor. A person may also require chemotherapy after the surgery.

The type of teratoma and whether it is malignant may also affect the treatment options.

For example, with ovarian teratomas, the four standard treatments are:

For an individual with a stage 1 ovarian teratoma, surgery may be the only necessary treatment if the tumor is small and easy to remove. If a person requires chemotherapy, the American Cancer Society notes that doctors typically prescribe three cycles of chemotherapy on the PEB regimen. This chemotherapy regimen includes the drugs cisplatin, etoposide, and bleomycin.

A teratoma is a type of germ cell tumor that can be benign or cancerous. These tumors may contain several different types of tissue, such as hair, muscle, and bone. They usually occur in the ovaries in females, the testicles in males, and the tailbone in children. However, they can sometimes appear elsewhere in the body.

The treatment varies depending on the tumor’s location, size, and stage, but it typically involves surgical removal and chemotherapy.