Astrocytoma: A tumor that begins in the brain or spinal cord in small, star-shaped cells called astrocytes. The location of the tumor depends on the age of the person. In adults, astrocytomas most often arise in the cerebrum, whereas in children, they may arise in the brain stem, cerebrum, and cerebellum.
Quick GuideDementia, Alzheimer's Disease, and Aging Brains
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Last Editorial Review: 6/9/2016