Germ cell tumors
Germ cells 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.
Germ cell cancers represent about 4 percent of all childhood cancers.
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. They account for about 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.
What causes germ cell tumors?
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, 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.
What are the symptoms of germ cell tumors?
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 ($-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
- Abnormal shape, or irregularity in, testicular size
The symptoms of germ cell tumors may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.
How are germ cell tumors diagnosed?
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, genetic studies and measurement of AFP and $ - HCG
- Multiple imaging studies, including:
- Computed tomography scan (also called a CT or CAT scan). A diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
- Magnetic resonance imaging (MRI). A diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
- X-ray. A diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
- Ultrasound (also called sonography) A diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.
- Bone scans. Pictures or x-rays taken of the bone after a dye has been injected that is absorbed by bone tissue. These are used to detect tumors and bone abnormalities.