user: What is (are) Childhood Central Nervous System Germ Cell Tumors ?

assistant: Key Points
                    - Childhood central nervous system (CNS) germ cell tumors form from germ cells.     - There are different types of childhood CNS germ cell tumors.          - Germinomas     - Nongerminomas        - The cause of most childhood CNS germ cell tumors is not known.    - Signs and symptoms of childhood CNS germ cell tumors include unusual thirst, frequent urination, early puberty, or vision changes.    - Imaging studies and tests are used to detect (find) and diagnose childhood CNS germ cell tumors.    - A biopsy may be done to be sure of the diagnosis of CNS germ cell tumor.    - Certain factors affect prognosis (chance of recovery).
                
                
                    Childhood central nervous system (CNS) germ cell tumors form from germ cells.
                    Germ cells are a type of cell that form as a fetus (unborn baby) develops. These cells later become sperm in the testicles or eggs in the ovaries. Sometimes while the fetus is forming, germ cells travel to other parts of the body and grow into germ cell tumors. Germ cells tumors that form in the brain or spinal cord are called CNS germ cell tumors.   The most common places for one or more central nervous system (CNS) germ cell tumors to form is near the pineal gland and in an area of the brain that includes the pituitary gland and the tissue just above it. Sometimes germ cell tumors may form in other areas of the brain.    This summary is about germ cell tumors that start in the central nervous system (brain and spinal cord). Germ cell tumors may also form in other parts of the body. See the PDQ summary on Childhood Extracranial Germ Cell Tumors Treatment for information on germ cell tumors that are extracranial (outside the brain).    CNS germ cell tumors usually occur in children, but may occur in adults. Treatment for children may be different than treatment for adults. See the following PDQ summaries for information about treatment for adults:         -  Adult Central Nervous System Tumors Treatment     -  Extragonadal Germ Cell Tumors Treatment         For information about other types of childhood brain and spinal cord tumors, see the PDQ summary on Childhood Brain and Spinal Cord Tumors Treatment Overview.
                
                
                    There are different types of childhood CNS germ cell tumors.
                    There are different types of CNS germ cell tumors. The type of CNS germ cell tumor depends on what the cells look like under a microscope. This summary is about the treatment of the following types of CNS germ cell tumors:     Germinomas    Germinomas are the most common type of CNS germ cell tumor and have a good prognosis.       Nongerminomas    Some nongerminomas make hormones. CNS teratomas are a type of nongerminoma that does not make hormones. They may have different kinds of tissue in them, such as hair, muscle, and bone. Teratomas are described as mature or immature, based on how normal the cells look under a microscope. Sometimes teratomas are a mix of mature and immature cells.     Other types of nongerminomas include the following:            -  Choriocarcinomas make the hormone beta-human chorionic gonadotropin (-hCG).     -  Embryonal carcinomas do not make hormones.     - Yolk sac tumors make the hormone alpha-fetoprotein (AFP).     - Mixed germ cell tumors are made of more than one kind of germ cell.