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Germ cells are special cells in a developing embryo (fetus) that become the eggs in girls’ ovaries or the sperm in boys’ testicles. Rarely, during development of the embryo, these cells may also travel to other areas of the body and form a tumor. A tumor is a mass that forms when normal cells change and grow uncontrollably. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). Germ cells may travel to the chest, abdomen, or brain.
This summary covers germ cell tumors that are extracranial (occurring in places other than the brain) and extragonadal (occurring outside of the reproductive organs). Extracranial, extragonadal germ cell tumors that occur in early childhood generally begin in the sacrum and the coccyx, which are the lowest parts of the spinal column. Extracranial, extragonadal germ cell tumors found in teenagers and young adults are often located in the mediastinum (center of the chest).
For information on a germ cell tumor in the brain, read about childhood central nervous system tumors.
Find out more about basic terms used in this section.
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