Types of brain and spinal cord tumors in children
Tumors can form in almost any type of tissue or cell in the brain or spinal cord. Some tumors have a mixture of cell types. Tumors in different areas of the central nervous system may be treated differently and have a different prognosis (outlook).
Brain tumors in children are more likely to start in the lower parts of the brain, such as the cerebellum and brain stem, than they are in adults. But they can start in the upper parts of the brain as well.
Gliomas are not a specific type of tumor. Glioma is a general term for a group of tumors that start in glial cells. A number of tumors can be considered gliomas, including glioblastoma (also known as glioblastoma multiforme), anaplastic astrocytoma, astrocytoma, oligodendroglioma, ependymoma, brain stem glioma, and optic glioma. Most brain and spinal cord tumors in children are gliomas.
Most tumors that develop in the brain itself start in cells called astrocytes, a kind of glial cell. These tumors are called astrocytomas.
Most astrocytomas can spread widely throughout, and intermingle with, the normal brain tissue, which can make them very hard to remove by surgery. Sometimes they spread along the CSF pathways. It is very rare for them to spread outside of the brain or spinal cord.
Astrocytomas are classified as high grade, intermediate grade, or low grade, based largely on how the cells look under the microscope.
Intermediate- and high-grade astrocytomas: These tumors tend to grow quickly and spread into the surrounding normal brain tissue. The highest-grade astrocytoma, known as glioblastoma (or glioblastoma multiforme), is the fastest growing. Anaplastic astrocytomas are also in this group.
Low-grade astrocytomas: These tumors tend to be slow growing and are the most common type in children. Some special types, known as non-infiltrating astrocytomas, tend to grow very slowly and do not grow into (infiltrate) nearby tissues, so they often have a good prognosis.
- Pilocytic astrocytomas are slow growing and rarely infiltrate nearby tissues. They most commonly occur in the cerebellum but can also begin in the optic nerve, hypothalamus, brain stem, or other areas. They account for nearly 1 out of 5 brain tumors in children.
- Subependymal giant cell astrocytomas (SEGAs) occur in the ventricles. They are also slow growing and rarely infiltrate nearby tissues. These tumors are almost always linked with tuberous sclerosis (an inherited condition that can also cause epilepsy, mental retardation, and tumors of the skin and kidneys).
- Fibrillary (diffuse) astrocytomas are also slow-growing tumors, although they can infiltrate nearby tissues, which can make them hard to remove with surgery. Though these tumors are thought of as low grade, they tend to become more aggressive and fast growing over time.
- Optic gliomas are low-grade astrocytomas that start in the optic nerves (the nerves leading from the eyes to the brain). They are often linked with an inherited condition called neurofibromatosis type 1. These tumors rarely cause death but may cause vision loss and injury to nearby brain tissue.
These tumors start in brain glial cells called oligodendrocytes. These tumors tend to grow slowly, but like astrocytomas, most of them can grow into nearby brain tissue and cannot be completely removed by surgery. Oligodendrogliomas rarely spread along the CSF pathways and even less frequently spread outside the brain or spinal cord. Only about 2% of brain tumors in children are oligodendrogliomas. As with astrocytomas, they can become more aggressive over time.
About 5% of brain tumors in children are ependymomas. These tumors start in the ependymal cells that line the ventricles or central canal of the spinal cord. They can range from fairly low-grade (slow growing) tumors to higher grade ones, which are called anaplastic ependymomas.
Ependymomas may spread along the CSF pathways but do not spread outside the brain or spinal cord. These tumors may block the flow of CSF out of the ventricles, causing the ventricles to become very large – a condition called hydrocephalus.
Unlike astrocytomas and oligodendrogliomas, ependymomas usually do not grow into normal brain tissue. As a result, some (but not all) ependymomas can be removed and cured by surgery. But because they can spread along ependymal surfaces and CSF pathways, treating them can sometimes be difficult. Spinal cord ependymomas have the greatest chance of being cured, but treatment can cause side effects related to nerve damage.
These tumors contain more than one cell type. For example, oligoastrocytomas have some of the same types of cells as both oligodendrogliomas and astrocytomas. Treatment is typically based on the fastest growing component of the tumor.
Brain stem gliomas
This term refers to the location of the tumor, rather than the type of cell it starts in. These tumors start in the brain stem. A small number of brain stem gliomas occur as a tumor with very distinct edges (called a focal brain stem glioma). More often, brain stem gliomas grow diffusely throughout the brain stem, rather than growing as a focal tumor. These tumors often start in the pons, where they are called diffuse intrinsic pontine gliomas.
About 10% to 20% of brain tumors in children are brain stem gliomas. Nearly all of these tumors are some type of astrocytoma.
Primitive neuroectodermal tumors (PNETs)
These tumors start in primitive (immature) cells of the central nervous system called neuroectodermal cells. About 1 out of 5 brain tumors in children are this type. They are more common in younger children than older ones, and are rare in adults. PNETs tend to grow quickly and often spread throughout the CSF pathways. These tumors sometimes have different names depending on where they occur.
Medulloblastomas: PNETs that start in the cerebellum are called medulloblastomas. About 15% of childhood brain tumors are medulloblastomas. These tumors can often be treated effectively and tend to have a better prognosis than PNETs in other parts of the brain.
Pineoblastomas: PNETs are called pineoblastomas when they occur in the pineal gland. These tumors are usually harder to treat than medulloblastomas.
These slow-growing tumors start above the pituitary gland but below the brain itself. They may press on the pituitary gland and the hypothalamus, causing hormone problems. Because craniopharyngiomas start very close to the optic nerves, they can also cause vision problems. This makes them hard to remove completely without damaging the child’s vision or hormone balance.
Mixed glial and neuronal tumors
Certain tumors that develop in children and young adults (and rarely in older adults) have both glial and neuronal cell components. They tend to have a fairly good prognosis.
- Pleomorphic xanthoastrocytoma (PXA) and dysembryoplastic neuroepithelial tumors (DNETs) look as if they could grow quickly when viewed under the microscope, but these tumors tend to be fairly benign, and most are cured by surgery alone.
- Ganglioglioma is a type of tumor that has both mature neurons and glial cells. Most can be cured by surgery alone or surgery combined with radiation therapy.
Choroid plexus tumors
These rare tumors start in the choroid plexus within the ventricles of the brain. Most are benign (choroid plexus papillomas) and are cured by surgery. However, some are malignant (choroid plexus carcinomas).
This type of tumor starts in Schwann cells that surround and insulate cranial nerves and other nerves. Schwannomas are usually benign tumors. They often form near the cerebellum on the cranial nerve responsible for hearing and balance, in which case they are called vestibular schwannomas or acoustic neuromas. They may also develop on spinal nerves past the point where they have left the spinal cord. When this is the case, they can press on the spinal cord, causing weakness, sensory loss, and bowel and bladder problems.
These tumors are rare in children. When schwannomas are found in a child, particularly if there are tumors on both sides of the head, it often means the child has an inherited tumor syndrome such as neurofibromatosis type 2 (see “What are the risk factors for brain and spinal cord tumors in children?”).
Other tumors that start in or near the brain
These tumors begin in the meninges, the layers of tissue that surround the outer part of the brain and spinal cord. Meningiomas cause symptoms by pressing on the brain or spinal cord. They are much less common in children than in adults.
Meningiomas are almost always benign and are usually cured by surgery. Some, however, are located very close to vital structures in the brain and cannot be cured by surgery alone.
Meningiomas are often assigned a grade based on how the cells look under the microscope:
- Grade I tumors, which look most like normal cells, make up about 80% to 90% of meningiomas.
- Grade II (atypical) meningiomas look slightly more abnormal.
- Grade III (anaplastic) meningiomas, which look the most abnormal, make up only about 1% to 3% of meningiomas.
Higher-grade meningiomas are more likely to come back after treatment, and some grade III meningiomas can spread to other parts of the body.
These tumors start in the bone at the base of the skull or at the lower end of the spine. These tumors don’t start in the central nervous system, but they can cause injury to the nervous system by pressing on it. Chordomas tend to come back after treatment if not removed completely, causing more damage. They usually do not spread to other organs. Chordomas are much more common in adults than in children. For more information on these tumors, see our document Bone Cancer.
Germ cell tumors
These rare tumors develop from germ cells, which normally form eggs in women and sperm in men. During the normal development of the embryo and fetus, germ cells travel to the ovaries or testicles and develop into eggs or sperm cells. Sometimes, however, a few germ cells may not move properly and end up in abnormal locations such as the brain. They may then develop into germ cell tumors, similar to those that can form in the ovaries or testicles.
Germ cell tumors of the nervous system usually occur in children, most often in the pineal gland or above the pituitary gland. These tumors can sometimes be diagnosed without a biopsy by measuring certain chemicals in the CSF or blood.
The most common germ cell tumor of the nervous system is the germinoma. Other tumors that start in germ cells include choriocarcinomas, embryonal carcinomas, teratomas, and yolk sac tumors (endodermal sinus tumors).
These nerve cell tumors are the third most common cancer in children. Neuroblastomas rarely develop in the brain or spinal cord; most develop from nerve cells inside the abdomen or chest. This type of cancer is most commonly diagnosed during early infancy. For more information, see our separate document, Neuroblastoma.
Lymphomas are cancers that start in cells called lymphocytes (one of the main cell types of the immune system). Most lymphomas start in other parts of the body, but some may start in the CNS. CNS lymphomas are rare in children. For more information on childhood lymphomas, see our separate document, Non-Hodgkin Lymphoma in Children.
Tumors that start in the pituitary gland are almost always benign (non-cancerous). But they can still cause problems, depending on how quickly they grow and compress nearby structures and whether or not they make too much of any kind of hormone. For more information, see our document, Pituitary Tumors.
Cancers that spread to the brain from other sites
Sometimes brain tumors are found not to have started in the brain but rather to have metastasized (spread) from some other part of the body. Tumors that start in other organs and then spread to the brain are called metastatic or secondary brain tumors (as opposed to primary brain tumors, which start in the brain). This is important because metastatic and primary brain tumors are often treated differently.
In children, metastatic tumors to the brain are much less common than primary brain tumors. Childhood leukemias can sometimes spread to the CSF around the brain and spinal cord. When this happens, the cancer is still considered a leukemia (the cancer cells in the CSF are leukemia cells), so doctors use treatments directed at the leukemia. For more information, see our document Childhood Leukemia.
This document covers only primary brain tumors.
Last Medical Review: 03/22/2013
Last Revised: 03/22/2013