An astrocytoma is a tumor that arises from astrocytes a type of glial cell.
Glial cells are the most common cellular component of the brain.
Glial cells have an enormous potential for abnormal growth and are the chief source of CNS tumors. Approximately half of all primary brain tumors are glial cell neoplasms and more than three quarters of all gliomas are astrocytomas. Astrocytomas are a heterogeneous group of tumors that are grouped by grades. The first symptom of a brain tumor of any type can be a headache. The reason that patients get headaches with brain tumors is that these masses cause increased pressure in the brain.