As a fetus develops, certain cells form sperm in the testicles or eggs in the ovaries. Sometimes these cells travel to other parts of the body and grow into germ cell tumors. This summary is about germ cell tumors that form in parts of the body that are
Mature teratomas are the most common type of extracranial germ cell tumor. The cells of mature teratomas look very much like normal cells. Mature teratomas are benign and not likely to become cancer.
Immature teratomas have cells that look very different from normal cells. Immature teratomas are not cancer. They often contain several different types of tissue such as hair, muscle, and bone.
Malignant germ cell tumors are cancer. There are three types of malignant germ cell tumors:
Gonadal germ cell tumors form in the testicles or ovaries.
Testicular germ cell tumors usually occur before the age of 4 years or in teenagers and young adults.
Testicular germ cell tumors in teenagers and young adults are different from those that form in early childhood. They are more like testicular cancer in adults. Testicular germ cell tumors are divided into two main types, seminoma and nonseminoma. (See the PDQ summary on
Boys older than 14 years with testicular germ cell tumors are treated in pediatric cancer centers, but the treatment is similar to that used in adults. (See the PDQ summary on
Ovarian germ cell tumors form in egg-making cells in an ovary. These tumors are more common in teenage girls and young women. Most ovarian germ cell tumors are benign teratomas. (See the PDQ summary on
Extragonadal germ cell tumors form in areas other than the testicles or ovaries.
Most germ cell tumors that are not in the testicles, ovaries, or brain, form along the midline of the body. This includes the following:
In younger children, extragonadal extracranial germ cell tumors usually occur at birth or in early childhood. Most of these tumors are teratomas in the sacrum or coccyx.
In older children, teenagers, and young adults, extragonadal extracranial germ cell tumors are often in the mediastinum.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Possible risk factors for extracranial germ cell tumors include the following:
Different tumors may cause the following signs and symptoms. Other conditions may cause these same symptoms. A doctor should be consulted if any of these problems occur.
The following tests and procedures may be used:
Most malignant germ cell tumors release tumor markers. The following tumor markers are used to detect extracranial germ cell tumors:
The prognosis for childhood extracranial germ cell tumors, especially ovarian germ cell tumors, is good.