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Types of Brain Tumours

There are more than 100 different types of brain tumors. Tumours are usually named after the type of cell they develop from. One example is a glioma, which grows out of glial cells. Tumours may also be described based on their location, such as a brainstem glioma.

Sometimes the same tumour may have different names, which can be confusing. The name of a tumour can change as researchers learn more details about tumour cells.

You may also hear tumours being described in two other general ways.

1. Where they begin to grow: primary and secondary tumours

A primary brain tumour develops directly in the brain. Most brain tumours in children are primary brain tumours.

A secondary tumour is rare in children. It develops first somewhere else in the body, such as in the bones or skin. When these abnormal bone or skin cells spread to the brain, they are called a secondary tumour.

2. How fast they are growing: benign and malignant brain tumours. This may also be described as the grade of a tumour.

A benign brain tumour is not cancerous. The cells in the tumour are growing slowly. Many benign brain tumours can be removed by surgery and they do not grow back. However, some benign brain tumours can be dangerous. This is because they are located in a part of the brain that is difficult to reach by surgery or in an important part of the brain that could be harmed by surgery.

A malignant brain tumour is considered a cancer. This means the abnormal cells in the tumour are making copies of themselves quickly. As a result, the tumour grows quickly, and tumour cells can spread to other parts of the brain or spine. This is called metastasis. However, in many cases, cancerous tumours can be treated with good success. They rarely spread outside the central nervous system (CNS).

What is grading?

Grading is a system that indicates how aggressively tumour cells are growing. Grade 1 tumours are considered benign and they do not grow fast. Grade 4 tumours are malignant, or cancerous, and they grow very quickly. The grade of a tumour is used to plan treatment and predict the course of the disease.

A doctor called a pathologist studies the tumour cells under a microscope to give the tumour a grade.

What is staging?

Staging determines the type of treatment that is most effective. This depends on a number of factors such as the child’s age, the type and size of the tumour, and whether it has spread to other parts of the body.

To stage the tumour, the following diagnostic tools are used: computerized tomography ( CT) scans, magnetic resonance imaging ( MRI), lumbar puncture, and sometimes bone marrow studies.

Types of brain tumours

Tumour cell type

Comments

Gliomas:

May be located anywhere within the major areas of the brain (cerebral hemispheres, cerebellum, brainstem) or spinal cord

Pilocytic astrocytoma

Low grade glioma, benign, World Health Organization (WHO) grade I; includes optic nerve and hypothalamic gliomas, which are located in the optic chiasm (which is part of the optic nerve system in the brain) or a part of the brain called the sellar region

Fibrillary astrocytoma

Low grade glioma, benign, WHO grade II

Pilomyxoid astrocytoma

Low grade glioma, benign, WHO grade I (mostly seen in infants; often more aggressive behaviour than pilocytic astrocytoma)

Anaplastic astrocytoma

High grade glioma, malignant, WHO grade III

Glioblastoma multiforme

High grade glioma, malignant, WHO grade IV

Diffuse pontine glioma

Malignant glioma located in the brainstem

Medulloblastoma

A type of primitive neuroectodermal tumour (PNET) located in the cerebellum and fourth ventricle (a fluid-filled space in the brain). There are three types of medulloblastoma: classic, desmoplastic, and large cell/anaplastic

Ependymoma:

Usually located in lining of the ventricles

Myxopapillary ependymoma

WHO grade I

Benign ependymoma

WHO grade II

Anaplastic ependymoma

WHO grade III

Germ cell tumours:

 

Germinoma

Most common type

Non-germinomatous germ cell tumours

Also known as secreting germ cell tumours

Teratoma

Non-germinoma, non-secreting tumours; may be benign or malignant

Craniopharyngioma

Slow-growing, benign tumour located in the sellar region above the pituitary gland

Other central nervous system tumours:

 

Dysembryoplastic neuro-epithelial tumour

Benign tumour located within the brain, often causes seizures

Choroid plexus tumours

Located in a part of the brain called the choroid plexus, most often in the lateral ventricles

Associated with overproduction of cerebrospinal fluid (CSF)

Meningioma

Rare benign tumour located in external lining of brain or spinal cord

Pituitary adenoma

Rare benign tumour of the pituitary gland

Rhabdoid tumour

Rare, fast-growing malignant tumour found mostly in infants

Schwannoma

Benign, slow-growing tumour of the peripheral nerves

 

Eric Bouffet, MD, FRCPC

7/10/2009




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