Germ cell tumors are malignant (cancerous) or non-malignant (benign, non-cancerous) tumors that are comprised mostly of germ cells. Germ cells are the cells that develop in the embryo (fetus, or unborn baby) and become the cells that make up the reproductive system in males and females. These germ cells follow a midline path through the body after development and descend into the pelvis as ovarian cells or into the scrotal sac as testicular cells. Most ovarian tumors and testicular tumors are of germ cell origin. The ovaries and testes are called gonads.
 
Tumor sites outside the gonad are called extragonadal sites. The tumors also occur along the midline path and can be found in the head, chest, abdomen, pelvis, and sacrococcygeal (lower back) area.
 
Germ cell tumors are rare, as only about 2.4 children in one million will develop one of these tumors in a given year. Germ cell tumors account for 4 percent of all cancers in children and adolescents under the age of 20 years.
 
Germ cell tumors can spread (metastasize) to other parts of the body. The most common sites for metastasis are the lungs, liver, lymph nodes, and central nervous system. Rarely, germ cell tumors can spread to the bone, bone marrow, and other organs.

The cause of germ cell tumors is not completely understood. A number of inherited defects have also been associated with an increased risk of developing germ cell tumors including the central nervous system and genitourinary tract malformations and major malformations of the lower spine. Specifically, males with cryptorchidism (failure of the testes to descend into the scrotal sac) have an increased risk to develop testicular germ cell tumors. Cryptorchidism can occur alone, however, and is also present in some genetic syndromes.
 
In addition, cells from testicular germ cell tumors can have structural chromosome abnormalities involving chromosome #12, which may explain the uncontrolled cell growth and tumor formation.
 
Some genetic syndromes caused by extra or missing sex chromosomes can cause incomplete or abnormal development of the reproductive system.

The following are the most common symptoms of germ cell tumors. However, each child may experience symptoms differently. Symptoms vary depending on the size and location of the tumor. Symptoms may include:

• a tumor, swelling, or mass that can be felt or seen
• elevated levels of alpha-fetoprotein (AFP)
• elevated levels of beta-human chorionic gonadotropin (β-HCG)
• constipation, incontinence, and leg weakness can occur if the tumor is in the sacrum (a segment of the vertebral column that forms the top part of the pelvis) compressing structures

In addition to a complete medical history and physical examination, diagnostic procedures for germ cell tumors may include:

• biopsy - a sample of tissue is removed from the tumor and examined under a microscope.
• complete blood count (CBC) - a measurement of size, number, and maturity of different blood cells in a specific volume of blood.
• additional blood tests - may include blood chemistries, evaluation of liver and kidney functions, and genetic studies.

Specific treatment for germ cell tumors will be determined by your child's physician based on:

• your child's age, overall health, and medical history
• extent of the disease
• your child's tolerance for specific medications, procedures, or therapies
• expectations for the course of the disease
• your opinion or preference

Treatment may include (alone or in combination):

• surgery (to remove tumor and involved organs)
• chemotherapy
• radiation
• bone marrow transplantation
• supportive care (for the effects of treatment)
• hormonal replacement (if necessary)
• antibiotics (to prevent/treat infections)
• continuous follow-up care (to determine response to treatment, detect recurrent disease, and manage the late effects of treatment)