Extragonadal Germ Cell Tumors Health Article

Definition

Germ cells are primitive cells within the body that normally mature into ova (egg) or sperm cells. More than 90% of all germ cell tumors are gonadal; that is, they develop in the ovaries or the testes (the gonads). The remaining 5-10% of germ cell tumors arise outside of the gonads: these are the extragonadal germ cell tumors. These tumors occur mostly in the chest, lower back, and head.

Description

Extragonadal germ cell tumors are related to developmental problems that occur prior to birth. In the growing embryo, germ cells migrate to the immature ovaries or testes. In some instances, these cells fail to move to the gonads and end up in the midchest area between the lungs (mediastinum), the lowest part of the back (presacral area), or near the pea-sized gland between the two hemispheres of the brain (pineal gland). When these germ cells grow in these extragonadal sites, they sometimes develop into tumors. These tumors can be benign (noncancerous) or malignant (cancerous).

Benign extragonadal germ cell tumors are called benign teratomas. Malignant extragonadal germ cell tumors are subdivided into seminoma and nonseminoma. The nonseminoma germ cell tumors include: embryonal carcinoma, malignant teratoma, endodermal sinus tumor, choriocarcinoma, and mixed germ cell tumors. The specific category of extragonadal germ cell tumor that is present has a major influence on both treatment and prognosis.

Demographics

Extragonadal germ cell tumors are quite rare. One new case is diagnosed annually for every 1 million people in the United States.

In young children, extragonadal germ cell tumors tend to occur primarily in the presacral area. The majority of these tumors are benign.

In adults, extragonadal germ cell tumors tend to be in the mediastinum. Of these, approximately 40% are malignant.

Malignant extragonadal germ cell tumors occur with equal frequency in boys and girls. But, they are approximately nine times more likely to occur in men than in women.

Extragonadal germ cell tumors occur with equal frequency in members of all races and ethnic groups. There does not appear to be any relationship of extragonadal germ cell tumors to any geographic region.

Causes and symptoms

The cause, or causes, of extragonadal germ cell tumors are not known.

The symptoms of an extragonadal germ cell tumor depend on the type and location of the tumor.

Mediastinum

Germ cell tumors of the mediastinum are primarily diagnosed in men between the ages of 20 and 30. Symptoms include:

• chest pain
• breathing problems
• cough
• fever

Presacral area

Presacral germ cell tumors are primarily diagnosed in children under the age of six. These are generally seen as a mass in the lower abdomen or buttocks. Because of the size and location of the tumor, the patient may have difficulty passing urine or having a bowel movement. Tumors detected in children under the age of six months are benign in 98% of cases. Tumors detected in children over the age of six months are malignant in approximately 65% of cases.

Pineal area

Almost all pineal germ cell tumors occur in people under the age of 40. Symptoms include:

• headache
• nausea
• vomiting
• lethargy
• difficulty walking
• memory loss
• an inability to look upward
• uncontrolled eye movement
• double vision

In some cases, a pineal germ cell tumor can begin to produce hormones that can cause a child to enter puberty at an abnormally young age (precocious puberty).

Diagnosis

The diagnosis of an extragonadal germ cell tumor usually begins with a thorough physical examination. In cases where a presacral tumor is suspected, this will include a rectal examination and a pelvic examination in women. In cases where a germ cell tumor of the pineal area is suspected, a complete neurological examination will be performed.

Mediastinum

The first test for a tumor of the mediastinum is a standard chest x ray. This will detect the tumor and show its location in 95% of cases. This will be followed by a computed tomography (CT) scan of the chest to determine the size of the tumor and by a CT scan of the abdomen to see if there has been a spread (metastasis) to the liver or other abdominal sites.

Diagnosis is generally confirmed by taking a needle biopsy of the tumor. In this procedure, a needle is injected directly into the tumor and a sample is removed.

Certain types of nonseminomas can be detected via blood tests for levels of alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta-hCG).

Presacral area

Germ cell tumors of the presacral area are diagnosed by either magnetic resonance imaging (MRI) or ultrasound imaging techniques. These techniques allow for the determination of both the location and the precise size of the tumor. To check for metastases, a bone scan, chest x rays, and a CT scan of the lungs should be performed. Sometimes a bone marrow biopsy is also ordered.

Diagnosis of a presacral germ cell tumor is confirmed by a direct biopsy of the tumor. This may be either an excisional biopsy, in which the tumor is first removed, then examined; or, a needle biopsy, in which only a sample of the tumor is removed for examination.

Pineal area

A CT scan of the head will usually show a pineal tumor. An MRI scan, using gadolinium as a tracer chemical, may also be ordered.

Blood tests for AFP and beta-hCG may help to diagnose pineal area germ cell tumors. Tests for these chemicals on the cerebrospinal fluid (lumbar puncture) may also be ordered.

The diagnosis of a pineal area germ cell tumor is usually confirmed upon biopsy of the tumor after it has been removed from the patient.