Germ cells are special cells in a developing embryo—also called the fetus or unborn baby—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 cancerous or benign. A cancerous tumor is malignant, meaning it can spread to other parts of the body. A benign tumor means the tumor will not spread.
Types of Germ Cell Tumors
Germ cells may travel to the chest, abdomen, or brain. Germ cell tumors that form in the brain are called intracranial germ cell tumors. For information on a germ cell tumor in the brain, read about childhood central nervous system tumors. Extracranial germ cell tumors are found outside of the brain.
There are two different categories of germ cell tumors that start in the testicles or ovaries: seminomas and non-seminomas. Generally, non-seminomas tend to grow and spread more quickly than seminomas, but prompt diagnosis and treatment are important for both types of tumor.
Germ cell tumors outside of the brain can be divided into gonadal and extragonadal.
Gonadal germ cell tumors. Gonadal germ cell tumorsstart and stay in a child’s reproductive organs, which are the testicles or ovaries. For more information on a germ cell tumor in the reproductive organs, read about ovarian and testicular cancer.
Extragonadal germ cell tumors. Extragonadal germ cell tumors start in a child’s reproductive system but travel to different parts of the body. Germ cells that occur outside the gonads (reproductive organs) and outside the brain are called extragonadal and extracranial. These occur in early childhood generally and commonly 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, which is the center of the chest.
This summary covers extracranial, extragonadal germ cell tumors.
Looking for More of an Overview?
If you would like additional introductory information, explore this related item. Please note this link takes you to another section on Cancer.Net:
- Cancer.Net Patient Education Video: View a short video led by an ASCO expert in childhood cancer that provides basic information and areas of research.