Brain Tumour Classification
There are more than 120 types of brain tumours. Today, most medical institutions use the World Health Organization (WHO) classification system to identify brain tumours.
The WHO system classifies brain tumours by cell origin and how the cells behave, from the least aggressive (benign) to the most aggressive (malignant).
Some tumour types are assigned a grade, ranging from Grade I (least malignant) to Grade IV (most malignant), which signifies the rate of growth. There are variations in grading systems, depending on the tumour type.
The classification and grade of an individual tumour help predict its likely behavior.

Types of Brain Tumour
Astrocytomas
Astrocytomas are the most common type of Brain Tumour. An astrocytoma is a glioma that develops from star-shaped glial cells (astrocytes) that support nerve cells. Please see below for further details on the different categories of astrocytomas :
An Anaplastic Sstrocytoma is classified as a Grade III tumour.
Characteristics
Grows faster and more aggressively than grade II astrocytomas
Tumor cells are not uniform in appearance
Invades neighboring tissue
Common among men and women in their 30s-50s
More common in men than women
Accounts for two percent of all brain tumors
Treatment
Treatment depends on the location of the tumor and how far it has progressed. Surgery and radiation therapy, with chemotherapy during or following radiation, are the standard treatments. If surgery is not an option, then the doctor may recommend radiation and/or chemotherapy. Many clinical trials (experimental treatments) using radiation, chemotherapy, or a combination are available for initial and recurrent anaplastic astrocytomas.
A Pilocytic Astrocytoma (Grade I) also called Juvenile Pilocytic Astrocytoma (JPA)
Characteristics
Slow growing, with relatively well-defined borders
Grows in the cerebrum, optic nerve pathways, brain stem and cerebellum
Occurs most often in children and teens
Accounts for two percent of all brain tumors
Treatment
Surgery is the standard treatment. If the tumour cannot be completely resected, radiation or chemotherapy may be given. Chemotherapy may be given to very young children instead of radiation therapy to avoid damage to the developing brain. Some of these tumors can progress to a higher grade, so it is important to be diligent about following up with the medical team after treatment.
The WHO classifies a Low-Grade Astrocytoma as a Grade II tumour.
Characteristics
Slow growing
Rarely spreads to other parts of the CNS
Borders not well defined
Common among men and women in their 20s-50s
Treatment
Treatment depends on the size and location of the tumor. The doctor will most likely perform a biopsy or surgery to remove the tumor. Partial resections or inoperable tumors may be treated with radiation. Recurring tumors may require additional surgery, radiation and/or chemotherapy.
A Glioblastoma Multiforme is classified as a grade IV astrocytoma. It is also referred to as a glioblastoma or GBM.
Characteristics
Most invasive type of glial tumor
Commonly spreads to nearby tissue
Grows rapidly
Includes distinct genetic subtypes
May be composed of several different kinds of cells (i.e., astrocytes, oligodendrocytes)
May have evolved from a low-grade astrocytoma or an oligodendroglioma
Common among men and women in their 50s-70s
More common in men than women
Accounts for 17 percent of all primary brain tumors
Treatment
Standard treatment is surgery followed by radiation therapy or a combination of radiation therapy and chemotherapy. If surgery is not an option, the doctor may administer radiation therapy followed by or in conjunction with chemotherapy. Many clinical trials (experimental treatments) using radiation, chemotherapy, or a combination are available for initial and recurrent GBM. Clinical trials using molecularly targeted therapies showing success in other cancers are also being tested in GBM patients.
Acoustic Neuroma
An acoustic neuroma is also known as a schwannoma, vestibular schwannoma, or neurilemmoma.
Characteristics
Arises from cells that form a protective sheath around nerve fibers
Typically grows around the eighth cranial nerve, but can be found around other cranial or spinal nerves
Symptoms
Hearing loss in one ear
Dizziness or vertigo
Tinnitus (ringing in the ear)
Tingling or numbness in the face
Walking and balance problems
Lack of coordination
Treatment
An acoustic neuroma may be observed in order to monitor its growth, or surgery may be performed. The goal of surgery is the complete removal of the tumor without harming the seventh cranial nerve (which controls facial movement) or causing hearing loss. Radiosurgery can be a viable option for many patients. This focused, high-energy radiation prevents the growth of acoustic neuromas, but actual shrinkage of the tumor may never occur or may take several months.
Brain Stem Glioma
Characteristics
Named for its location at the base of the brain
Can range from low grade to high grade
Occurs most often in children between three and ten years of age, but can occur in adults
Symptoms
Headaches
Nausea
Speech or balance abnormalities
Difficulty swallowing
Weakness or numbness of the arms and/or legs
Facial weakness
Double vision
Symptoms can develop slowly and subtly and may go unnoticed for months. In other cases, the symptoms may arise abruptly. A sudden onset of symptoms tends to occur with rapidly growing, high-grade tumors.
Treatment
Surgery may not be an option because the brain stem controls vital life functions and can easily be damaged. Radiation therapy can reduce symptoms and help slow the tumor’s growth. Low-grade brain stem gliomas can have very long periods of remission.
Chordoma
Characteristics
Rare and low grade
Occurs at the sacrum, near the lower tip of the spine, or at the base of the skull
Originates from cells left over from early fetal development
Invades the bone and soft tissues but rarely the brain tissue
Can block the ventricles, causing hydrocephalus (water on the brain)
Can metastasize (spread) or recur
Symptoms
Double vision
Headaches
Treatment
Surgery and radiation therapy are the common forms of treatment. Chordomas at the base of the skull can be difficult to remove. Surgical resection may be possible if the tumor is located in the spine.
CNS Lymphoma
CNS Lymphoma is a type of cancer that develops in the lymphatic system. The lymphatic system is a network of small organs called lymph nodes and vessels (similar to blood vessels) that carry a clear, watery fluid called lymph throughout the body. This fluid supplies cells called lymphocytes that fight disease and infection. To correctly diagnose primary CNS Lymphoma, staging must be done. Staging is the process of using CT scanning to examine many parts of the body. Staging helps to confirm where the cancer originated and how far it has spread.
Characteristics
Very aggressive
Usually involves multiple tumors throughout the central nervous system (CNS)
More common in people whose immune systems are compromised
Often develops in the brain, commonly in the areas adjacent to the ventricles
Can be primary (originating in the brain) or secondary
Most common among men and women in their 60s-80s, but incidence is increasing in young adults
More common in men than women
Accounts for about two percent of all brain tumors
Symptoms
Headaches
Partial paralysis on one side of the body
Seizures
Cognitive or speech disorders
Vision problems
Treatment
Radiation therapy, chemotherapy, and steroids are the most common forms of treatment. Surgery is rarely an option because there are usually multiple lesions. However, a biopsy at the start of steroid treatment can be critical to ensure the correct diagnosis.
Craniopharyngioma
Characteristics
Most common in the parasellar region, an area at the base of the brain and near the optic nerves
Also grows in the regions of the optic nerves and the hypothalamus, near the pituitary gland
Tends to be low grade
Often accompanied by a cyst
Originates in cells left over from early fetal development
Occurs in children and men and women in their 50s and 60s
Symptoms
Headaches
Visual changes
Weight gain
Delayed development in children
Treatment
Surgery is the most common treatment. Radiation therapy may be used.
Ependymal Tumors
Ependymal tumors begin in the ependyma, cells that line the passageways in the brain where cerebrospinal fluid (CSF) is produced and stored. Ependymomas are classified as either supratentorial (in the cerebral hemispheres) or infratentorial (in the back of the brain). Variations of this tumor type include subependymoma, subependymal giant-cell astrocytoma, and malignant ependymoma. Ependymoblastoma, which occurs in infants and children under three years, is no longer considered a subtype of ependymoma. For ependymoblastoma, see primitive neuroectodermal tumor (PNET) in the Non-glial Tumors section.
Characteristics
Usually localized to one area of the brain
Develops from cells that line the hollow cavities at the bottom of the brain and the canal containing the spinal cord
Can be slow growing or fast growing
May be located in the ventricles (cavities in the center of the brain)
May block the ventricles, causing hydrocephalus (water on the brain)
Sometimes extends to the spinal cord
Common in children, and among men and women in their 40s and 50s
Occurrence peaks at age five and again at age 34
Accounts for two percent of all brain tumors
Symptoms
Severe headaches
Nausea and vomiting
Difficulty walking
Fatigue and sleepiness
Problems with coordination
Neck pain or stiffness
Visual problems
Treatment
The doctor will perform tests to determine if it has spread to the spinal cord. Surgery followed by radiation therapy is the usual course of treatment. A shunt may be needed to treat hydrocephalus caused by blockage of the ventricles.
Medulloblastoma
Characteristics
A type of primitive neuroectodermal tumor (PNET) (see below)
Often located in the cerebellum or near the brain stem
Can spread to the spinal cord through the cerebrospinal fluid (CSF)
May obstruct the fourth ventricle, causing hydrocephalus (water on the brain)
Occurs most often in children under the age of ten, but may occur in adults
Slightly more common in males than females
Symptoms
Headaches
Early morning vomiting
Lethargy or sleepiness
Lack of coordination
Double vision
Behavioral or personality changes
Signs of pressure seen behind the eye when examined with an ophthalmoscope
Treatment
Surgery is the standard treatment when possible. Chemotherapy is usually part of the treatment plan. Radiation of the brain and spine is often recommended in adults and children over three years of age. A shunt may be needed to treat hydrocephalus. This tumor may recur years later if not totally resected.
Meningioma
The Meningioma tumour grow from the meninges, the layers of tissue covering the brain and spinal cord. As they grow, meningiomas compress adjacent brain tissue. Symptoms are often related to this compression of brain tissue, which can also affect cranial nerves and blood vessels. In some cases, meningioma growth can also extend into the bones of the head and face, which may produce visible changes. Most meningiomas are considered nonmalignant or low grade tumors. However, unlike nonmalignant tumors elsewhere in the body, some of these brain tumors can cause disability and may sometimes be life threatening. In many cases, meningiomas grow slowly. Other meningiomas grow more rapidly or have sudden growth spurts. There is no way to predict the rate of growth of a meningioma or to know for certain how long a specific tumor was growing before diagnosis. Meningiomas are graded from low to high. The lower the grade, the lower the risk of recurrence and aggressive growth.
The WHO classification divides meningiomas into three grades:
Grade I: Benign Meningioma
Grade II: Atypical Meningioma
Grade III: Malignant (Anaplastic) Meningioma
Characteristics
May arise after previous treatment from ionizing radiation or excessive x-ray exposure
Common among women and men in their 40s-50s, but can occur at any age
Twice as common in women as in men
Accounts for 34 percent of all primary brain tumors
In very rare cases, can invade the skull or metastasize to the skin or lungs
Women with meningiomas can experience tumor growth during pregnancy
In rare cases, multiple meningiomas can develop at the same time in different parts of the brain and/or spinal cord
Symptoms
Seizures
Headaches
Nausea and vomiting
Vision changes
Behavioral and cognitive changes
Sometimes no symptoms occur and tumor is detected incidentally
Treatment
If there are no symptoms, the doctor may monitor the tumor with MRIs. Otherwise, surgery is the standard treatment. If the tumor cannot be completely resected or if it recurs, radiation therapy may be given as well. Chemotherapy for unresectable, aggressive, atypical, or recurrent meningiomas is being tested through clinical trials. Follow-up scans are needed indefinitely, because meningiomas can recur years or even decades after treatment.
Metastatic Brain Tumors
A metastatic, or secondary, brain tumour is one that begins as cancer in another part of the body. Some of the cancer cells may be carried to the brain by the blood or lymphatic fluid, or may spread from adjacent tissue. The site where the cancerous cells originated is referred to as the primary cancer. Metastatic brain tumours are often referred to as lesions or brain metastases. Metastatic brain tumours are the most common brain tumours. There has been an increase in metastatic lesions as people are surviving primary cancers for longer periods of time.
Characteristics
The primary cancer is usually in the lung, breast, colon, kidney, or skin (melanoma), but can originate in any part of the body
Most are located in the cerebrum, but can also develop in the cerebellum or brain stem
More than half of people with metastatic tumours have multiple lesions (tumours)
Common among middle-aged and elderly men and women
Symptoms
Seizures
Headaches
Behavioural and cognitive changes
Lack of coordination
Treatment
Surgery and radiosurgery are the standard treatments if lesions are limited in number and accessible. Both of these treatments may be followed by whole brain radiation therapy (WBRT). In cases of multiple lesions, WBRT alone may be given. Chemotherapy specific to the brain-located metastatic tumour may be used.
Mixed Glioma
Mixed Glioma is often a combination of an astrocytoma and an oligodendroglioma (see oligodendroglioma for more).
Characteristics
Composed of two or more types of glioma cells
Graded according to the most aggressive type of tumor cells
Common among men and women in their 20s-50s
Accounts for one percent of all brain tumors
Symptoms
Headaches
Seizures
Weakness or paralysis
Nausea and vomiting
Visual problems
Behavioral and cognitive changes
Treatment
Mixed gliomas are generally treated for the most anaplastic (cancerous) type of cell found in the tumor. For example, in the case of a tumor composed of an anaplastic astrocytoma and a low-grade oligodendroglioma, the treatment would be based on the anaplastic astrocytoma – the more aggressive of the two cell types.
Oligodendroglioma
The Oligodendroglioma tumor type develops from glial cells called oligodendrocytes.
Characteristics
Occurs frequently in the frontal or temporal lobes
Can be classified as low grade or high grade
Common among men and women in their 20s-40s, but can occur in children
More common in men than women
Accounts for two percent of all brain tumors
May be associated with 1p or 19q chromosomal losses
Symptoms
Seizures
Headaches
Behavioral and cognitive changes
Weakness or paralysis
Treatment
Treatment options depend on the grade of the tumor. If the tumor is low grade and symptoms are not severe, the doctor may decide to perform surgery, then “watch and wait” and evaluate tumor growth through MRIs. There is a malignant form called anaplastic oligodendroglioma and a mixed malignant astrocytoma-oligodendroglioma. The common treatment for these high-grade tumors is surgery followed by radiation therapy and/or chemotherapy. Both low- and high-grade oligodendrogliomas can recur. If a tumor recurs, the doctor will evaluate it for a second surgical procedure, radiation, and/or chemotherapy. Gene expression studies are used to classify gliomas based on certain characteristics, or genetic profiles. Oligodendrogliomas can be identified by deficiencies in certain chromosomes named 1p and 19q. Genetic profiling of oligodendrogliomas provides a more accurate predictor of prognosis and treatment options than does standard pathology.
Optic Nerve Glioma
Characteristics
Named for its location on or near the nerve pathways between the eyes and the brain
Can range from low grade to high grade
Occurs most often in infants and children, but can occur in adults
Symptoms
Headaches
Progressive loss of vision
Double vision
Treatment
Surgery is standard treatment, usually followed by radiation therapy or chemotherapy. Chemotherapy may be given to very young children instead of radiation therapy to avoid damage to the developing brain.
Pituitary Tumours
The pituitary gland produces hormones that affect growth and the functions of other glands in the body. Certain pituitary tumors secrete abnormally high amounts of their respective hormones and cause related symptoms. Other pituitary tumors do not secrete hormones, but grow and compress brain tissue, causing other symptoms.
Characteristics
Named for its location on or near the pituitary gland, located at the center of the brain behind and above the nose
Can range from low grade to high grade
May cause excessive secretion of hormones
Common among men and women in their 50s-80s
Accounts for about 13 percent of all brain tumors
Symptoms
Headache
Depression
Vision loss
Nausea or vomiting
Behavioral and cognitive changes
Cessation of menstrual periods (amenorrhea)
Leaking of fluid from the breasts (galactorrhea)
Hair growth in women
Impotence in men
Abnormal growth of hands and feet
Abnormal weight gain
Treatment
If the tumor is large or compressing the optic nerve, standard treatment is surgery. This can be transphenoidal surgery, which gets access to the tumor by entering through the nasal passage. Radiation therapy may also be used. Some pituitary tumors may be treated with medication, and/or observed with MRI scans. Certain drugs can block the pituitary gland from making too many hormones. Follow up with an endocrinologist may be necessary to manage hormonal changes.
Primitive Neuroectodermal Tumour
There are several tumor types in this category. Names of specific Primitive Neuroectodermal Tumor (PNET) may be based on the tumor location. Examples include pineoblastoma (located in the pineal region, a form of pineal tumour), medulloblastoma (located in the cerebellum), and cerebral cortex PNET (located in the cerebral cortex).
Characteristics
Highly aggressive and tend to spread throughout the CNS
Grow from undeveloped brain cells
Commonly include cysts and calcification (calcium deposits)
Tend to be large
Symptoms
Can vary depending on location of tumor
Weakness or change in sensation on one side of the body
Morning headache or headache that goes away after vomiting
Nausea and vomiting
Seizures
Unusual sleepiness or lethargy
Behavioral or personality changes
Unexplained weight loss or weight gain
Treatment
Surgery is the standard treatment when possible. In adults and children over three years of age, surgery may be followed by radiation therapy to the whole brain and spinal cord, and chemotherapy. In children under three years of age, surgery may be followed by chemotherapy or a clinical trial of chemotherapy to delay or reduce the need for radiation therapy.
Schwannoma
The Schwannoma tumour is also known as vestibular schwannoma, neurilemmoma and acoustic neuroma (see “acoustic neuroma”).
Characteristics
Arises from cells that form a protective sheath around nerve fibers
Typically grows around the eighth cranial nerve, but can be found around other cranial or spinal nerves
Symptoms
Reduced hearing in the ear on the side of the tumor when eighth cranial nerve is involved Tinnitus (ringing in the ear)
Balance problems
Deficits depend on the nerve that is affected
Treatment
Surgery and radiotherapy are the most common forms of treatment. If the tumor is not completely removed, recurrence is likely.
Subependymoma
The Subependymoma tumor forms from ependymal cells, and is a variation of an ependymoma. Ependymal cells are cells line the passageway in the brain where cerebral spinal fluid (CSF) is produced and stored. Ependymal tumors are classified as either supratentorial (in the cerebral hemispheres) or infratentorial (in the back of the brain). See “Ependymoma” for more information.
Characteristics
Slow growing
Usually located in the fourth and lateral ventricles
More common in men than in women
Symptoms
Headaches
Nausea
Loss of balance
Sometimes no symptoms occur and tumor is detected incidentally
Treatment
Surgery will be performed when possible. Radiation therapy may be used if the tumor progresses or recurs. A shunt may be needed to treat hydrocephalus (water on the brain).
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