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Arthur & Sonia Labatt Brain Tumour Research Centre

Astrocytic tumours

Astrocytomas, the most common type of glioma, are also the most common type of primary brain tumour. They develop from star-shaped glial cells called astrocytes. They differ in their location within CNS, age and gender distribution, growth potential, extent of invasiveness, morphological features, tendency for progression and clinical course. According to International Agency for Research on Cancer (IARC), WHO guideline the following clinicopathological entities can be distinguished:

Diffuse astrocytomas

Low Grade diffuse astrocytoma image

Low Grade diffuse astrocytoma

Also known as lowgrade astrocytomas or grade I astrocytomas, these tumours contain cells that are relatively normal and are less malignant than the other two grades. They grow relatively slowly and may sometimes be completely removed through surgery. However, even well differentiated astrocytomas are life threatening if they are inaccessible.

 

Anaplastic astrocytomas

Also called midgrade or grade II astrocytomas, anaplastic astrocytomas grow more rapidly than well differentiated astrocytomas and contain cells with some malignant traits. Surgery followed by radiation, and sometimes chemotherapy, is used to treat anaplastic astrocytomas.

stoma multiforme image

Glioblastoma multiforme (GBM)

As the name "multiforme" implies GBMs are known for their regional pathological heterogeneity. These tumours, sometimes called high-grade or grade III astrocytomas, grow rapidly, invade nearby tissue and contain cells that are very malignant. The pathological characteristics include increased cellularity, nuclear atypia, cellular pleomorphism and high mitotic activity. Microvascular proliferation and necrosis is also present. Doctors usually treat glioblastomas with surgery followed by radiation therapy and, sometimes, chemotherapy. Glioblastomas multiforme are among the most common and devastating primary brain tumours that strike adults.

Pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma image

This neoplasm typically develops in children and young adults with superficial location in the cerebral hemisphere. Two third of the patients are less than 18 years old. Most of the pleomorphic xanthoastrocytoma are classified as grade II in the WHO scheme. Because of the superficial cerebral location of the lesion, many patients present with a fairly long history of seizures. Cerebral and spinal cord cases have symptoms that reflect the sites of involvement.

 

Juvenile Pilocytic astrocytoma

Juvenile Pilocytic astrocytoma image

The juvenile pilocytic astrocytoma (JPA) is the most common tumour of childhood. It can arise throughout the central nervous system from the optic nerve to conus medullaris. Sites include: (1) optic nerve (optic nerve glioma) (2) Optic chiasm/hypothalamus (Chiasmatic or hypothalamic glioma), (3) thalamus and basal ganglia. (4) cerebral hemispheres, (5) cerebellum (cerebellar asdtrocytoma) and (6) brain stem (dorsally exophytic brain stem glioma).


Symptoms: Headache, nausea, vomiting and problems with muscle coordination (ataxia).

Treatment: This is one of the lowgrade gliomas. It is very slow growing and often can be cured with surgery alone. When a JPA occurs in another area of the brain, such as the optic chiasm, it is sometimes impossible to totally remove surgically because of its location. Under such circumstances, it may be treated with either radiation therapy or chemotherapy.

Optic Nerve Glioma

These tumours are found on or near the nerves that travel between the eye and brain vision centers. They are particularly common in people who have neurofibromatosis. Treatment usually includes surgery or radiation therapy.

Brain Stem Glioma

Brain stem gliomas account for 20% of childhood tumours. They most frequently afflict children between the ages of 3 and 10 years and they range from very lowgrade astrocytomas, like the juvenile pilocytic astrocytoma, to the rapidly anaplastic glioblastoma multiforme. They are named by their location at the base of the brain rather than the cells they contain.

Symptoms: Nausea, headache, speech or balance abnormalities, difficulty with swallowing and weakness or numbness of the arms or legs. In some patients, the symptoms of the tumour develop insidiously and as much as a year passes before they are recognized. In others, symptoms develop abruptly, a pattern that tends to relate to more rapidly growing tumours.

Treatment: Surgery is not usually used to treat brain stem gliomas because of their vulnerable location. Radiation therapy sometimes helps to reduce symptoms and improve survival by slowing tumour growth. Tumours in this region of the brain are uniformly dangerous, but those of a low grade may have very long periods of remission.