What is an anaplastic astrocytoma?
An anaplastic astrocytoma is a high-grade, or malignant, glioma, a tumor of the glial (supportive) tissue of the brain. The term astrocytoma and glioma are often used interchangeably. Anaplastic astrocytoma and glioblastoma multiforme, another type of astrocytoma, account for approximately 10 percent of pediatric central nervous system tumors.
As you read further below, you will find general information about anaplastic astrocytomas. If you would like to view summary information about brain tumors first, see the overview on brain tumors.
Where do anaplastic astrocytomas occur?
Anaplastic astrocytomas may appear in several areas of the brain. Approximately 65 percent arise in the cerebral hemispheres, the top part of the brain. About 20 percent occur in the area of the thalamus and hypothalamus or the diencephalon, the area responsible for identification of sensation, such as temperature, pain and touch, regulation of appetite/weight and body temperature, as well as connecting the brainstem to the cortex.
Another 15 percent can occur in the region of the cerebellum and brain stem known as the posterior fossa.
The median age at diagnosis is 9 to 10 years old, and these tumors occur with equal frequency in boys and girls.
What causes an anaplastic astrocytoma?
Most anaplastic astrocytomas and high-grade gliomas occur sporadically or without identifiable cause. They do, however, occur with increased frequency in families with the following conditions.
- neurofibromatosis type I
- Li-Fraumeni syndrome
- hereditary nonpolyposis colon cancer
- tuberous sclerosis
- Anaplastic astrocytomas have also been associated with exposure to vinyl chloride and to high doses of radiation therapy to the brain.
What are the symptoms of an anaplastic astrocytoma?
Anaplastic astrocytomas of the cerebral hemispheres and the diencephalon (also called supratentorial anaplastic astrocytomas) produce a variety of symptoms as a result of increased pressure within the head, as well as more localizing symptoms related to their specific location, rate of growth and associated inflammation.
The duration of symptoms varies from slow, subtle onsets to more abrupt presentations. Each child may experience different symptoms. The following are the most common symptoms of an anaplastic astrocytoma:
- headache and lethargy
symptoms of increased pressure within the brain, including:
- headache (generally upon awakening in the morning).
- compression of surrounding brain structures; depending on the location of the tumor, increased pressure can cause:
- weakness and other motor dysfunction neuroendocrine abnormalities
- changes in behavior or thought processes
The symptoms of a brain tumor may resemble other conditions or medical problems. Always consult your child’s physician for a diagnosis.
How are anaplastic astrocytomas classified?
Gliomas, tumors that arise from the glial cells of the brain, are heterogeneous tumors that are classified according to their most aggressive appearing elements. An anaplastic astrocytoma is a type of glioma.
The World Health Organization classification scheme includes 4 grades of glioma. Anaplastic astrocytoma is a grade III tumor. It originates from the type of glial cell called an astrocyte. It is an aggressive tumor that frequently infiltrates adjacent normal brain tissue and often spreads outside of the central nervous system.