Types of Germ Cell Tumors

NYU Langone pediatric oncologists are experts at distinguishing the various types of germ cell tumors that affect children and teens. These tumors arise in the reproductive cells, also called germ cells, which normally become eggs or sperm. They can develop in the ovaries, which contain eggs, or testicles, which have sperm. Germ cell tumors may spread to other parts of the body, such as the chest, abdomen, or tailbone. These growths are known as extragonadal tumors.

Germ cell tumors can also develop in a child’s brain or spinal cord, in particular the brain’s pineal gland. This gland produces the hormone melatonin, which helps regulate sleep. These are called intracranial germ cell tumors.

Germ cell tumors that appear outside the brain are called extracranial germ cell tumors. They can be benign, or noncancerous, or malignant, meaning cancerous. Sometimes, germ cell tumors have more than one type of cell. They are called mixed germ cell tumors.

At NYU Langone, specialists treat many different types of extracranial germ cell tumors in children and teens.

Gonadal Germ Cell Tumors

Gonadal germ cell tumors form in the ovaries or the testes. There are two types of germ cell tumors that start in the gonads, or reproductive organs: seminomas, which are slower-growing, and nonseminomas, which are faster-growing tumors. These germ cell tumors typically form during puberty.

Ovarian Germ Cell Tumors

Ovarian germ cell tumors usually affect one ovary and are most common in girls ages 10 to 14. Most cancerous ovarian germ cell tumors are a type called dysgerminoma, which can spread to other parts of the body. This type of cancer is rare, constituting just 2 percent of all ovarian cancers.

Many ovarian germ cell tumors are teratomas, noncancerous cysts that affect teens and women of childbearing age.

Testicular Germ Cell Tumors

Although more than 90 percent of adult testicular cancers start in sperm-producing germ cells, germ cell tumors account for up to three-quarters of testicular cancers in children. It is the most common cancer among boys and men ages 15 to 35. Testicular germ cell tumors are found mainly in boys younger than age four and in teenagers and young men. Slow-growing tumors called seminomas are most common in children who have entered puberty.

Extracranial Extragonadal Germ Cell Tumors

Extracranial extragonadal germ cell tumors occur in developing sperm or egg cells that travel to areas outside the testicles or ovaries, but do not reach the brain. They appear most commonly in the midline, which runs vertically from the pineal gland in the brain to the tailbone, or coccyx. The most common area is the mediastinum, the area between the lungs. These tumors can be benign or malignant, and they tend to affect boys and girls equally.

Extragonadal germ cell tumors are typically diagnosed at birth or during early childhood, although older children and teens can develop these tumors, usually in the mediastinum. Also at increased risk are children with rare genetic conditions, such as Klinefelter syndrome, when boys are born with an extra X chromosome.

Malignant extragonadal germ cell tumors can be seminomas or nonseminomas, and each is treated differently. Nonseminomas are cancerous tumors that grow quickly and tend to be large. They may press on organs or nerves, so they are more likely than seminomas to cause symptoms. These tumors include embryonal carcinomas, malignant teratomas, and yolk sac tumors. Nonseminomas usually require chemotherapy.

Seminomas are most likely to occur in the testicles or ovaries, but some may appear in the mediastinum or abdomen. They are cancerous and grow slowly, but they tend not to spread.

Sacrococcygeal teratomas are germ cell tumors found at birth or before birth by ultrasound. These tumors affect the tailbone and lower vertebrae of the spine. They are more common in girls than in boys.

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