This is a medical question of type : information 
 What is (are) Adult Central Nervous System Tumors ? 
 Key Points
                    - An adult central nervous system tumor is a disease in which abnormal cells form in the tissues of the brain and/or spinal cord.    - A tumor that starts in another part of the body and spreads to the brain is called a metastatic brain tumor.    - The brain controls many important body functions.     - The spinal cord connects the brain to nerves in most parts of the body.    - There are different types of brain and spinal cord tumors.          - Astrocytic Tumors     - Oligodendroglial Tumors     - Mixed Gliomas     - Ependymal Tumors     - Medulloblastomas     - Pineal Parenchymal Tumors     - Meningeal Tumors     - Germ Cell Tumors     - Craniopharyngioma (Grade I)        - Having certain genetic syndromes may increase the risk of a central nervous system tumor.     - The cause of most adult brain and spinal cord tumors is not known.    - The signs and symptoms of adult brain and spinal cord tumors are not the same in every person.     - Tests that examine the brain and spinal cord are used to diagnose adult brain and spinal cord tumors.    - A biopsy is also used to diagnose a brain tumor.         - Sometimes a biopsy or surgery cannot be done.        - Certain factors affect prognosis (chance of recovery) and treatment options.
                
                
                    An adult central nervous system tumor is a disease in which abnormal cells form in the tissues of the brain and/or spinal cord.
                    There are many types of brain and spinal cord tumors. The tumors are formed by the abnormal growth of cells and may begin in different parts of the brain or spinal cord. Together, the brain and spinal cord make up the central nervous system (CNS).   The tumors may be either benign (not cancer) or malignant (cancer):         - Benign brain and spinal cord tumors grow and press on nearby areas of the brain. They rarely spread into other tissues and may recur (come back).     - Malignant brain and spinal cord tumors are likely to grow quickly and spread into other brain tissue.         When a tumor grows into or presses on an area of the brain, it may stop that part of the brain from working the way it should. Both benign and malignant brain tumors cause signs and symptoms and need treatment.   Brain and spinal cord tumors can occur in both adults and children. However, treatment for children may be different than treatment for adults. (See the PDQ summary on Childhood Brain and Spinal Cord Tumors Treatment Overview for more information on the treatment of children.)   For information about lymphoma that begins in the brain, see the PDQ summary on Primary CNS Lymphoma Treatment.
                
                
                    A tumor that starts in another part of the body and spreads to the brain is called a metastatic brain tumor.
                    Tumors that start in the brain are called primary brain tumors. Primary brain tumors may spread to other parts of the brain or to the spine. They rarely spread to other parts of the body.   Often, tumors found in the brain have started somewhere else in the body and spread to one or more parts of the brain. These are called metastatic brain tumors (or brain metastases). Metastatic brain tumors are more common than primary brain tumors.    Up to half of metastatic brain tumors are from lung cancer. Other types of cancer that commonly spread to the brain include:         -  Melanoma.    -  Breast cancer.    -  Colon cancer.    -  Kidney cancer.    -  Nasopharyngeal cancer.    -  Cancer of unknown primary site.        Cancer may spread to the leptomeninges (the two innermost membranes covering the brain and spinal cord). This is called leptomeningeal carcinomatosis. The most common cancers that spread to the leptomeninges include:         -  Breast cancer.    - Lung cancer.    -  Leukemia.    -  Lymphoma.        See the following for more information from PDQ about cancers that commonly spread to the brain or spinal cord:         -  Adult Hodgkin Lymphoma Treatment     -  Adult Non-Hodgkin Lymphoma Treatment     -  Breast Cancer Treatment     -  Carcinoma of Unknown Primary Treatment     -  Colon Cancer Treatment     -  Leukemia Home Page     -  Melanoma Treatment     -  Nasopharyngeal Cancer Treatment     -  Non-Small Cell Lung Cancer Treatment     -  Renal Cell Cancer Treatment     -  Small Cell Lung Cancer Treatment
                
                
                    The brain controls many important body functions.
                    The brain has three major parts:          - The cerebrum is the largest part of the brain. It is at the top of the head. The cerebrum controls thinking, learning, problem solving, emotions, speech, reading, writing, and voluntary movement.     - The cerebellum is in the lower back of the brain (near the middle of the back of the head). It controls movement, balance, and posture.     - The brain stem connects the brain to the spinal cord. It is in the lowest part of the brain (just above the back of the neck). The brain stem controls breathing, heart rate, and the nerves and muscles used to see, hear, walk, talk, and eat.
                
                
                    The spinal cord connects the brain to nerves in most parts of the body.
                    The spinal cord is a column of nerve tissue that runs from the brain stem down the center of the back. It is covered by three thin layers of tissue called membranes. These membranes are surrounded by the vertebrae (back bones). Spinal cord nerves carry messages between the brain and the rest of the body, such as a message from the brain to cause muscles to move or a message from the skin to the brain to feel touch.
                
                
                    There are different types of brain and spinal cord tumors.
                    Brain and spinal cord tumors are named based on the type of cell they formed in and where the tumor first formed in the CNS. The grade of a tumor may be used to tell the difference between slow-growing and fast-growing types of the tumor. The World Health Organization (WHO) tumor grades are based on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread.      WHO Tumor Grading System       - Grade I (low-grade)  The tumor cells look more like normal cells under a microscope and grow and spread more slowly than grade II, III, and IV tumor cells. They rarely spread into nearby tissues. Grade I brain tumors may be cured if they are completely removed by surgery.    - Grade II  The tumor cells grow and spread more slowly than grade III and IV tumor cells. They may spread into nearby tissue and may recur (come back). Some tumors may become a higher-grade tumor.    - Grade III  The tumor cells look very different from normal cells under a microscope and grow more quickly than grade I and II tumor cells. They are likely to spread into nearby tissue.    - Grade IV (high-grade)  The tumor cells do not look like normal cells under a microscope and grow and spread very quickly. There may be areas of dead cells in the tumor. Grade IV tumors usually cannot be cured.        The following types of primary tumors can form in the brain or spinal cord:     Astrocytic Tumors    An astrocytic tumor begins in star-shaped brain cells called astrocytes, which help keep nerve cells healthy. An astrocyte is a type of glial cell. Glial cells sometimes form tumors called gliomas. Astrocytic tumors include the following:            -  Brain stem glioma (usually high grade): A brain stem glioma forms in the brain stem, which is the part of the brain connected to the spinal cord. It is often a high-grade tumor, which spreads widely through the brain stem and is hard to cure. Brain stem gliomas are rare in adults. (See the PDQ summary on Childhood Brain Stem Glioma Treatment for more information.)     -  Pineal astrocytic tumor (any grade): A pineal astrocytic tumor forms in tissue around the pineal gland and may be any grade. The pineal gland is a tiny organ in the brain that makes melatonin, a hormone that helps control the sleeping and waking cycle.      -  Pilocytic astrocytoma (grade I): A pilocytic astrocytoma grows slowly in the brain or spinal cord. It may be in the form of a cyst and rarely spreads into nearby tissues. Pilocytic astrocytomas can often be cured.      -  Diffuse astrocytoma (grade II): A diffuse astrocytoma grows slowly, but often spreads into nearby tissues. The tumor cells look something like normal cells. In some cases, a diffuse astrocytoma can be cured. It is also called a low-grade diffuse astrocytoma.      -  Anaplastic astrocytoma (grade III): An anaplastic astrocytoma grows quickly and spreads into nearby tissues. The tumor cells look different from normal cells. This type of tumor usually cannot be cured. An anaplastic astrocytoma is also called a malignant astrocytoma or high-grade astrocytoma.      -  Glioblastoma (grade IV): A glioblastoma grows and spreads very quickly. The tumor cells look very different from normal cells. This type of tumor usually cannot be cured. It is also called glioblastoma multiforme.            See the PDQ summary on Childhood Astrocytomas Treatment for more information about astrocytomas in children.       Oligodendroglial Tumors    An oligodendroglial tumor begins in brain cells called oligodendrocytes, which help keep nerve cells healthy. An oligodendrocyte is a type of glial cell. Oligodendrocytes sometimes form tumors called oligodendrogliomas. Grades of oligodendroglial tumors include the following:            -  Oligodendroglioma (grade II): An oligodendroglioma grows slowly, but often spreads into nearby tissues. The tumor cells look something like normal cells. In some cases, an oligodendroglioma can be cured.      -  Anaplastic oligodendroglioma (grade III): An anaplastic oligodendroglioma grows quickly and spreads into nearby tissues. The tumor cells look different from normal cells. This type of tumor usually cannot be cured.             See the PDQ summary on Childhood Astrocytomas Treatment for more information about oligodendroglial tumors in children.       Mixed Gliomas    A mixed glioma is a brain tumor that has two types of tumor cells in it  oligodendrocytes and astrocytes. This type of mixed tumor is called an oligoastrocytoma.            -  Oligoastrocytoma (grade II): An oligoastrocytoma is a slow-growing tumor. The tumor cells look something like normal cells. In some cases, an oligoastrocytoma can be cured.     -  Anaplastic oligoastrocytoma (grade III): An anaplastic oligoastrocytoma grows quickly and spreads into nearby tissues. The tumor cells look different from normal cells. This type of tumor has a worse prognosis than oligoastrocytoma (grade II).             See the PDQ summary on Childhood Astrocytomas Treatment for more information about mixed gliomas in children.       Ependymal Tumors    An ependymal tumor usually begins in cells that line the fluid -filled spaces in the brain and around the spinal cord. An ependymal tumor may also be called an ependymoma. Grades of ependymomas include the following:            -  Ependymoma (grade I or II): A grade I or II ependymoma grows slowly and has cells that look something like normal cells. There are two types of grade I ependymoma  myxopapillary ependymoma and subependymoma. A grade II ependymoma grows in a ventricle (fluid-filled space in the brain) and its connecting paths or in the spinal cord. In some cases, a grade I or II ependymoma can be cured.     -  Anaplastic ependymoma (grade III): An anaplastic ependymoma grows quickly and spreads into nearby tissues. The tumor cells look different from normal cells. This type of tumor usually has a worse prognosis than a grade I or II ependymoma.             See the PDQ summary on Childhood Ependymoma Treatment for more information about ependymoma in children.       Medulloblastomas    A medulloblastoma is a type of embryonal tumor. Medulloblastomas are most common in children or young adults.      See the PDQ summary on Childhood Central Nervous System Embryonal Tumors Treatment for more information about medulloblastomas in children.       Pineal Parenchymal Tumors     A pineal parenchymal tumor forms in parenchymal cells or pineocytes, which are the cells that make up most of the pineal gland. These tumors are different from pineal astrocytic tumors. Grades of pineal parenchymal tumors include the following:            -  Pineocytoma (grade II): A pineocytoma is a slow-growing pineal tumor.     -  Pineoblastoma (grade IV): A pineoblastoma is a rare tumor that is very likely to spread.            See the PDQ summary on Childhood Central Nervous System Embryonal Tumors Treatment for more information about pineal parenchymal tumors in children.       Meningeal Tumors    A meningeal tumor, also called a meningioma, forms in the meninges (thin layers of tissue that cover the brain and spinal cord). It can form from different types of brain or spinal cord cells. Meningiomas are most common in adults. Types of meningeal tumors include the following:            -  Meningioma (grade I): A grade I meningioma is the most common type of meningeal tumor. A grade I meningioma is a slow-growing tumor. It forms most often in the dura mater. A grade I meningioma can be cured if it is completely removed by surgery.     -  Meningioma (grade II and III): This is a rare meningeal tumor. It grows quickly and is likely to spread within the brain and spinal cord. The prognosis is worse than a grade I meningioma because the tumor usually cannot be completely removed by surgery.            A hemangiopericytoma is not a meningeal tumor but is treated like a grade II or III meningioma. A hemangiopericytoma usually forms in the dura mater. The prognosis is worse than a grade I meningioma because the tumor usually cannot be completely removed by surgery.        Germ Cell Tumors    A germ cell tumor forms in germ cells, which are the cells that develop into sperm in men or ova (eggs) in women. There are different types of germ cell tumors. These include germinomas, teratomas, embryonal yolk sac carcinomas, and choriocarcinomas. Germ cell tumors can be either benign or malignant.     See the PDQ summary on Childhood Central Nervous System Germ Cell Tumors Treatment for more information about childhood germ cell tumors in the brain.       Craniopharyngioma (Grade I)    A craniopharyngioma is a rare tumor that usually forms in the center of the brain just above the pituitary gland (a pea-sized organ at the bottom of the brain that controls other glands). Craniopharyngiomas can form from different types of brain or spinal cord cells.     See the PDQ summary on Childhood Craniopharyngioma Treatment for more information about craniopharyngioma in children.