An astrocytoma is a brain tumor that begins in astrocytes—a type of glial cell that supports nerve cells in the brain. Astrocytomas can be benign or malignant and typically occur in the brainstem, cerebellum, cerebrum, hypothalamus or optic nerves. Tumors that start in glial cells are called gliomas and are named for the specific kind of glial cell in which they originate: astrocytes, oligodendrocytes or ependymocytes. Astrocytomas are the most common form of gliomas found in children—accounting for nearly half of all pediatric brain and spinal cord tumors. Like all gliomas, astrocytomas are divided into four grades based on factors including the rate of tumor growth, level of cell abnormality and effects on surrounding healthy tissue. Low-grade astrocytomas (grades I and II) are often localized to one area and typically behave less aggressively. While considered benign, these tumors...
