What is Astrocytoma?

Pediatric astrocytoma (sometimes called glioma) is one of the most common types of brain tumor that can develop in children. It arises from a specific type of cell in the brain, called an astrocyte. Astrocytomas are divided into subgroups based on their grade and their location in the brain, so the same tumor can have several different names. Treatment for various types of astrocytoma can be very different, so it is important that your doctor provides you with the name as well as the grade of the tumor.

Tumor Grade

The grade is determined by what the tumor tissue looks like under the microscope and depends on features such as the number of cells that are actively dividing and how the tumor cells look compared to normal cells.

Currently we divide astrocytomas into four grades based on criteria set by the World Health Organization. In general, the lower the grade of a tumor, the less aggressive its behavior.

• Grade 1 astrocytoma grows very slowly and often can be cured by surgery alone. The most common type of grade 1 astrocytoma is called juvenile pilocytic astrocytoma (JPA).

• Grade 2 astrocytoma grows faster than grade 1 astrocytomas, but is still relatively slow growing. These tumors may also be called fibrillary astrocytoma.

• Grade 3 astrocytoma is also called anaplastic astrocytoma. It grows faster than grade 1 and 2 tumors and can progress to a grade 4 tumor.

• Grade 4 astrocytoma is also called glioblastoma multiforme (GBM). It is one of the fastest growing brain tumors and can spread to other parts of the brain. Grade 1 and 2 astrocytomas are often referred to as low-grade gliomas and grade 3 and 4 astrocytomas as high-grade gliomas.


Location in the Brain

Subtypes of pediatric astrocytomas classified by their location in the brain include:

• Cerebellar astrocytoma
• Optic pathway glioma
• Hypothalamic/thalamic glioma
• Tectal glioma
• Brainstem glioma

High-grade gliomas are mainly located within the cerebral hemispheres but can also occur in the thalamus or the brainstem. A high-grade glioma that is located within the pons is a special subtype of astrocytoma called diffuse intrinsic pontine glioma.

Based on this classification system, your care providers could call the same tumor several different names. For example, a grade 1 astrocytoma that is located in the optic pathway could be called a juvenile pilocytic astrocytoma, a grade 1 glioma, or an optic pathway glioma.

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Low-grade glioma

High-grade glioma

Brainstem glioma