Pathology refers to the examination of tissue under a microscope to find out whether it is cancerous or non-cancerous and to determine the type of tumour it is. Many different types of tumours can affect the brain and spinal cord.
Tumours are usually named after the type of cell they develop from. For example, a glioma grows out of the glial cells in the brain.
Tumours may also be described based on the area of the brain they develop in, such as a brain stem glioma.
- Many childhood brain tumours develop in the lower parts of the brain, such as the cerebellum or fourth ventricle. These are called infratentorial tumours or posterior fossa tumours.
- Tumours that develop in the upper portion of the brain, such as the cerebrum, are classified as supratentorial.
- Tumours that develop in the centre of the brain are known as sellar, suprasellar or pineal region tumours.
- Sellar tumours develop in the area of the hypothalamus, pituitary gland and optic nerve.
- Suprasellar tumours develop in the area just above the sellar area around the thalamus.
- Pineal region tumours develop at the back of the third ventricle, at the top of the brain stem.
Childhood brain tumours can also be described by how fast they grow. Brain tumours can be malignant (cancerous) or benign (non-cancerous). In a malignant tumour, the abnormal cells grow and divide quickly and out of control (this is also called high grade). As a result, the tumour grows quickly and cancer cells can invade nearby tissues and spread to other parts of the brain or spine.
In a benign tumour, the cells grow much slower (also called low grade) and usually do not invade surrounding tissues or spread to other areas of the brain.
While the terms malignant and benign are useful in describing tumours in other parts of the body, they are not as useful when describing central nervous system (CNS) tumours. Because the brain is enclosed in the rigid skull, there is very little room for a tumour to grow. Even benign, slow-growing tumours can cause serious problems and even death if they develop in an area that is difficult to reach by surgery, or in an area that could be harmed by surgery.
Different tumours within the same classification, such as the gliomas, can be either fast growing or slow growing. Some slow-growing tumours also have the potential to develop into more aggressive tumours.
Types of brain tumours
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Astrocytoma: - fibrillary astrocytomas
- anaplastic astrocytomas
- glioblastoma multiforme
| - Low-grade, slow-growing glioma, (sometimes considered benign)
- Low-grade, slow-growing glioma,
- High-grade glioma, malignant
- High-grade glioma, malignant
|
Brain stem glioma | Can be malignant or low-grade Can be focal (localized) or diffuse (infiltrating) |
Oligodendroglioma | Can be low-grade or high-grade (anaplastic) |
Optic nerve and hypothalamic glioma | Low-grade glioma |
Ependymoma | Usually low-grade and located in the ventricles Can also be high-grade (anaplastic) |
Choroid plexus tumours - choroid plexus papilloma
- choroid plexus carcinoma
| Located in the choroid plexus often in the lateral ventricles - Slow-growing
- Fast-growing and likely to spread to other parts of the brain and spinal cord
|
Primitive neuroectodermal tumours (PNET) | |
Medulloblastoma | A type of PNET located in the cerebellum and fourth ventricle May spread to other parts of the brain and spinal cord Also known to spread outside of the CNS |
Pineal tumours | - Malignant, fast growing, high tendency to spread outside the CNS
- Slower-growing than pineoblastomas
|
Ependymoblastoma | Fast growing, rare |
Cerebral neuroblastoma | Neuroblastoma that occurs in the brain |
Germ cell tumours | |
Germinoma | Most common type |
Non-germinomatous germ cell tumours | Also known as secreting germ cell tumours Usually malignant and fast growing |
Teratoma | Non-germinoma, non-secreting tumours May be benign or malignant |
Pituitary adenoma | Slow growing, usually benign, rare |
Space-occupying tumour | |
Hormone-secreting tumours - prolactin secreting adenoma (prolactinoma)
- growth hormone secreting adenoma
- ACTH secreting adenoma
- TSH secreting adenoma
| |
Craniopharyngioma | Slow growing |
Mixed glial and neuronal tumours | |
Dysembryoplastic neuroepithelial tumour (DNET) | Slow growing |
Ganglioglioma | Slow growing, rarely malignant |
Schwannoma | Slow growing, rare |
Meningioma | Slow growing, rare |
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Once the type of tumour has been diagnosed, the doctor will also consider:
- the grade of the tumour (how abnormal the cancer cells look and behave)
- the stage of the cancer, including if it has spread (metastasized) and where it has spread
- prognostic factors (special characteristics that might influence the course of the disease)
- survival statistics for the particular type and stage of cancer
All of this information helps the doctor make a treatment plan for the child.
See a list of questions to ask your doctor about pathology and staging.