Germ Cell Tumor - Yolk Sac Tumor

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What are germ cell tumors?

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 cell 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.


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 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.


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 (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


•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, and genetic studies.


•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.


What are the different types of germ cells?

Diagnosis of germ cell tumors depends on the types of cells involved. The most common types of germ cell tumors include:

•teratomas
Teratomas contain cells from the three germ layers: ectoderm, mesoderm, and endoderm. Teratomas can be malignant or benign, depending on the maturity and other types of cells that may be involved. Teratomas are the most common germ cell tumor found in the ovaries. Sacrococcygeal (tail bone, or distal end of spinal column) teratomas are the most common germ cell tumors found in childhood. Because these sacrococcygeal tumors are often visible from the outside of the body, diagnosis is made early and treatment and/or surgery are initiated early, making the prognosis for this type of germ cell tumor very favorable.


•germinomas
Germinomas are malignant germ cell tumors. Germinomas are also termed dysgerminoma when located in the ovaries; and seminoma when located in the testes. Among children, germinoma, or dysgerminoma, occurs most frequently in the ovary of a pre-pubescent or adolescent female. Dysgerminoma is the most common malignant ovarian germ cell tumor seen in children and adolescents.


•endodermal sinus tumor or yolk sac tumors
Endodermal sinus tumor or yolk sac tumors are germ cell tumors that are most often malignant, but may also be benign. These tumors are most commonly found in the ovary, testes, and sacrococcygeal areas (tail bone, or distal end of spinal column). When found in the ovaries and testes, they are often very aggressive, malignant, and can spread rapidly through the lymphatic system and other organs in the body. Yolk sac tumors are the most common malignant testicular and ovarian tumors in children. Most yolk sac tumors will require surgery and chemotherapy, regardless of stage or presence of metastasis, because of the aggressive nature and recurrence of the disease.


•choriocarcinoma
Choriocarcinoma is a very rare, but often malignant germ cell tumor that arises from the cells in the chorion layer of the placenta (during pregnancy, a blood-rich structure through which the fetus takes in oxygen, food, and other substances while getting rid of waste products). These cells may form a tumor in the placental cells during pregnancy and spread (metastasize) to the infant and mother. When the tumor develops during pregnancy, it is called gestational choriocarcinoma. Gestational choriocarcinoma most often occurs in pregnant females that are 15 to19 years of age. If a non-pregnant young child develops choriocarcinoma from the chorion cells that originated from the placenta that are still in the body, the term used is non-gestational choriocarcinoma.


•embryonal carcinoma
Embryonal carcinoma cells are malignant cells that are usually mixed with other types of germ cell tumors. They occur most often in the testes. These types of cells have the ability to spread to other parts of the body. When these cells are mixed with an otherwise benign type of tumor (mature teratoma), the presence of embryonal carcinoma cells will cause it to become malignant (cancerous).

Many germ cell tumors have multiple types of cells involved. The diagnosis, treatment, and prognosis are based on the most malignant of the cells present and the majority type of cells that are present.


Treatment for germ cell tumors:

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)


Long-term outlook of a child with a germ cell tumor:

Prognosis greatly depends on:

•the extent of the disease.
•the size and location of the tumor.
•presence or absence of metastasis.
•the tumor's response to therapy.
•the age and overall health of your child.
•your child's tolerance of specific medications, procedures, or therapies.
•new developments in treatment.

As with any cancer, prognosis and long-term survival can vary greatly from individual to individual. Prompt medical attention and aggressive therapy are important for the best prognosis. Continuous follow-up care is essential for a child diagnosed with a germ cell tumor. Side effects of radiation and chemotherapy, as well as second malignancies, can occur in survivors of germ cell tumors. New methods are continually being discovered to improve treatment and to decrease side effects.