Types of Brain Tumors in Children

As a group, brain tumors are the most common solid tumor in children and teens. However, there are many different types of brain tumors. Here are some of the more common types of brain tumors affecting young people.

Brain tumor names can be confusing. If you have questions about the tumor you or your child has, ask your cancer care team.

How doctors classify brain and spinal cord tumors

Doctors look at several features of brain or spinal cord tumors to help guide treatment and predict outlook:

Tumor type (based on the type of cell it starts in): Tumors can form in almost any type of tissue or cell in the brain or spinal cord. Each type of tumor tends to start in certain areas and to grow in certain ways. The most common types of brain and spinal cord tumors in children and teens are described below.

Tumor grade: This describes how the tumor cells look under the microscope and how fast they are likely to grow and invade nearby tissues, on a scale from 1 to 4:

• Lower grade (grade 1 or 2) tumors tend to grow more slowly and are less likely to grow into (invade or infiltrate) nearby tissues.
• Higher grade (grade 3 or 4) tumors tend to grow quickly and are more likely to grow into nearby tissues. These tumors are malignant and often require more intensive treatment. 

Gene changes in the tumor cells: Even brain tumors of the same type can have different changes in their genes (DNA). These gene changes can affect how a tumor will behave or which treatment might work best. For example, some tumors can have mutations in one of the BRAF genes. These tumors may respond well to targeted therapy drugs called BRAF inhibitors like dabrafenib or vemurafenib.

Tumor location: Where the tumor is in the brain or spinal cord can affect what symptoms it causes, as well as which treatments might be best.

Gliomas

Gliomas are a large group of tumors that start in the brain’s support cells, called glial cells. There are 5 main categories of gliomas in children and teens:

• Pediatric-type diffuse low-grade gliomas
• Pediatric-type diffuse high-grade gliomas
• Circumscribed astrocytic gliomas
• Glioneuronal and neuronal tumors
• Ependymal tumors

Gliomas most often occur by chance. But certain types are sometimes associated with family cancer syndromes. For example:

• People with neurofibromatosis type 1 are at higher risk for developing a glioma in the optic pathway or other low grade glioma.
• People with tuberous sclerosis are at a higher risk of developing a unique type of brain tumor called a SEGA, or subependymal giant cell astrocytoma (a type of circumscribed astrocytic glioma).

Doctors determine the specific type of glioma based on the presence of glial cells, a person’s age, the location and grade of the tumor, and specific tumor gene changes.

Pediatric-type diffuse low-grade gliomas

Low grade (grade I or II) gliomas tend to grow slowly and are the most common type of glioma in children and teens. They include:

• Diffuse low grade glioma, with a MAPK pathway gene change
• Diffuse astrocytoma, MYB or MYBL1 gene change present
• Angiocentric glioma
• Polymorphous low-grade neuroepithelial tumor of the young

These tumors usually respond well to treatment, especially in older children and when the tumor can be completely removed by surgery. When the tumor has spread, the outlook is poorer.

Pediatric-type diffuse high-grade gliomas

High-grade (grade III or IV) gliomas tend to grow quickly and spread into the surrounding normal brain tissue. In the past, these tumors were called anaplastic astrocytoma (grade III) and glioblastoma multiforme (grade IV). There are several types of high-grade glioma:

• Diffuse pediatric-type high-grade gliomas without changes in the H3 or IDH genes, is the most common type. It makes up about 4 out of 10 pediatric high-grade gliomas. These tumors are difficult to treat. Treatment options and outlook for these tumors depend on certain other gene changes.
• Diffuse midline glioma is a tumor with an H3 K27 gene change that usually grows in the pons (brainstem), thalamus, or other areas in the center of the brain. When these tumors occur in the pons, it’s often called a diffuse intrinsic pontine glioma, or DIPG. These tumors are not common and tend to be very difficult to treat.
• Diffuse hemispheric glioma occurs in the cerebral hemispheres of the brain and has gene changes in H3 G34.
• Infant-type hemispheric glioma is a unique type of brain tumor in infants. It has gene changes similar to low-grade gliomas, even though it’s a high-grade tumor based on how it looks under the microscope. The outlook tends to be better for younger children with these tumors.

High grade gliomas can be very difficult to treat. Doctors and researchers are looking for better ways to treat these types of brain tumors.

Circumscribed astrocytic gliomas

Circumscribed astrocytic gliomas (sometimes called non-infiltrating astrocytic gliomas or astrocytomas) tend to grow slowly and do not grow into (infiltrate) nearby tissues. They can occur anywhere in the brain but are more common in the cerebellar, thalamic, and hypothalamic areas. There are several types:

• Pilocytic astrocytoma (also called juvenile pilocytic astrocytoma, or JPA) is the most common glioma in the cerebellum. It can also begin in the optic nerve, hypothalamus, brain stem, or other areas. These tumors account for nearly 1 out of 5 brain tumors in children.
• High-grade astrocytomas with piloid features are tumors that have features of pilocytic astrocytoma, but under the microscope appear to be growing and dividing more quickly. These tumors are more aggressive than most pilocytic astrocytomas.
• Pleomorphic xanthoastrocytoma is a grade II tumor that tends to grow slowly. Most can be cured by surgery alone.
• Subependymal giant cell astrocytomas (SEGA) occur in the ventricles (spaces in the brain). They are grade I tumors that tend to grow slowly and rarely grow into nearby tissues. These tumors are almost always linked with an inherited condition called tuberous sclerosis.
• Choroid glioma
• Astroblastoma, with changes in the MN1 gene

Circumscribed astrocytic gliomas usually respond well to treatment, especially in older children and when surgery can completely remove the tumor. When the tumor has spread, the outlook is poorer.

Glioneuronal and neuronal tumors

Certain tumors that develop in children and young adults (and rarely in older adults) are made of both glial and neuronal cells. They tend to have a good outlook.

• Ganglioglioma is a type of low-grade tumor that has both mature neurons and glial cells. These tumors most often occur in the cerebrum or brainstem and are sometimes found because they cause seizures.
• Dysembryoplastic neuroepithelial tumors (DNETs) are slow growing (grade II) tumors that tend to affect older children. They are most common in the temporal lobe of the brain and can cause seizures.
• Desmoplastic infantile ganglioglioma (DIG)/desmoplastic infantile astrocytoma (DIA) most often occurs in the first year of life. These tumors often have a good outlook when they can be removed with surgery.

Other tumors in this category are less common in children. They include:

• Papillary glioneuronal tumors
• Rosette-forming glioneuronal tumors
• Gangliocytomas
• Extraventricular neurocytomas
• Diffuse leptomeningeal glioneuronal tumors.

These tumors usually respond well to treatment, especially in older children and when surgery can completely remove the tumor. When the tumor has spread, the outlook is poorer.

Ependymomas

About 5% of brain tumors in children are ependymal tumors, called 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 grade III (fast growing) tumors, which are called anaplastic ependymomas. Anaplastic ependymomas are more difficult to treat than lower grade ependymomas.

Ependymomas may spread along the cerebrospinal fluid (CSF) pathways but do not spread outside the brain or spinal cord. They can block the flow of CSF out of the ventricles, causing the ventricles to become very large – a condition called hydrocephalus. This can cause symptoms like severe headaches and vomiting.

Unlike other gliomas, ependymomas usually do not grow into normal brain tissue. As a result, some (but not all) ependymomas can be removed and cured by surgery and radiation. They may be harder to treat if the tumor cannot be completely removed with surgery, the child is younger when the tumor is found, or certain gene changes are present in the tumor.

Embryonal tumors

Embryonal tumors start in early forms of nerve cells in the central nervous system. About 20% of brain tumors in children and teens are embryonal tumors. They are more common in younger children than in older ones and are rare in adults. Embryonal tumors tend to grow quickly and often spread through the CSF.

Medulloblastomas are the most common type of embryonal tumor. These tumors start in the cerebellum. There are several different types of medulloblastomas, based on how the tumor cells look under a microscope and on which gene mutations the cells have. Some types tend to have a better outlook than others, and doctors are working to determine how this might affect treatment.

Medulloblastomas can often be treated effectively and tend to have a better outlook than embryonal tumors in other parts of the brain. 

Other, less common types of embryonal tumors include:

• Atypical teratoid/rhabdoid tumor (ATRT)
• Embryonal tumor with multilayered rosettes
• Central nervous system (CNS) ganglioneuroblastoma or neuroblastoma
• Cribriform neuroepithelial tumor

Choroid plexus tumors

These rare tumors start in the choroid plexus, the area that makes cerebrospinal fluid (CSF) within the ventricles of the brain. Most are a benign type called choroid plexus papillomas and can be cured by surgery. However, some are choroid plexus carcinomas, which are malignant (cancer).

Schwannomas (neurilemmomas)

Schwannomas are usually benign. They start in Schwann cells, which surround and insulate cranial nerves and other nerves.

• They often form near the cerebellum on the cranial nerve responsible for hearing and balance. These are called vestibular schwannomas or acoustic neuromas.
• They may also develop on spinal nerves, just past the point where the nerve branches off from the spinal cord. When this happens, the tumor can press on the spinal cord, causing weakness, sensory loss, and bowel and bladder problems.

These tumors are rare in children and young adults. Children and teens with schwannomas, especially those with tumors on both sides of the head, often have an inherited tumor syndrome such as neurofibromatosis type 2. 

Other tumors that start in or near the brain

Germ cell tumors

These rare tumors develop from germ cells, which normally form egg cells in women and sperm cells in men. During normal development before birth, germ cells usually travel to the ovaries or testicles and develop into egg or sperm cells. Sometimes, some germ cells do not move where they should and end up in locations such as the brain. These cells can develop into germ cell tumors in the central nervous system (CNS), similar to those that can form in the ovaries or testicles.

Germ cell tumors of the CNS are more common in children and teens, most often in the pineal gland or above the pituitary gland in the hypothalamus. These tumors can sometimes be diagnosed without a biopsy by measuring certain chemicals (called AFP and β-HCG) in the cerebrospinal fluid (CSF) or blood.

Types of germ cell tumors include:

• Germinomas (the most common type of CNS germ cell tumor)
• Teratomas
• Choriocarcinomas
• Embryonal carcinomas
• Yolk sac tumors (endodermal sinus tumors)

In some cases, tumors can grow from several types of cells. These mixed tumors, which can have features of choriocarcinoma, embryonal carcinoma, and/or yolk sac tumors, are called non-germinomatous germ cell tumors (NGGCT).

Pituitary adenomas

Pituitary tumors are rare in children. They are almost always non-malignant tumors called pituitary adenomas, but they can cause problems because of where they are located and any hormones they might make. Large pituitary adenomas can press on the optic nerves (nerves to the eyes), causing vision loss or changes. They can also disrupt the pituitary gland’s normal ability to make hormones that impact growth, puberty, metabolism, and other important body functions. To learn more, see Pituitary Tumors.

Craniopharyngioma

These slow-growing tumors start above the pituitary gland but below the brain itself. They account for about 4% of brain tumors in children and teens. These tumors 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 vision or hormone balance. To learn more, see Pituitary Tumors.

Pineoblastoma

Some types of brain tumors occur in the pineal gland, a small gland in the middle of the brain. These tumors used to be grouped with embryonal tumors like medulloblastoma, but are now called pineal parenchymal tumors. These include:

• Pineoblastoma
• Pineocytoma
• Papillary tumor of the pineal region
• Pineal parenchymal tumor of intermediate differentiation
• Desmoplastic myxoid tumor of the pineal region, with a SMARCB1 gene change

These tumors are rare and can be hard to treat. They are often treated like embryonal tumors.

Meningiomas

Meningiomas form in layers of tissue called the meninges 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 and teens than in adults.

Most meningiomas are non-malignant and can be treated with surgery. Some, however, are located very close to vital structures in the brain and cannot be treated with surgery alone.

Higher-grade meningiomas are considered cancerous and are more likely to come back after treatment or spread to other parts of the body.

To learn more, see Meningioma.

Chordomas

Chordomas do not start in the central nervous system (CNS), but they can harm important nearby nerves or tissues by pressing on them. They are actually a type of bone cancer that starts in the bone at the base of the skull or at the lower end of the spine called the sacrum. These tumors tend to come back if they are not removed completely, causing more damage. They usually do not spread to other organs. Chordomas are much more common in adults than in children and teens. For more on these tumors, see Bone Cancer.

Neuroblastomas

These nerve cell tumors are the third most common cancer in children. They most often develop from nerves in the belly or chest, but rarely can develop in the brain or spinal cord. This type of cancer is most common during the first few years of life. For more information, see Neuroblastoma.

Lymphomas

Lymphomas are cancers that start in cells called lymphocytes, which are white blood cells that are part of the immune system. Most lymphomas start in other parts of the body like the lymph nodes and spleen, but a small portion start in the central nervous system (CNS) and are called primary CNS lymphomas. These tumors are rare in children. For more on childhood lymphomas, see Lymphoma in Children.

Cancers that spread to the brain from other parts of the body

Sometimes tumors found in the brain have metastasized (spread) there from another 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 distinction is important because metastatic and primary brain tumors are often treated differently.

In children and teens, metastatic brain tumors are much less common than primary brain tumors. Childhood leukemias can sometimes spread to the fluid around the brain and spinal cord (cerebrospinal fluid or CSF). When this happens, the cancer is still considered leukemia, so doctors use treatments directed at leukemia. For more information, see Childhood Leukemia.