Astrocytomas are intracranial tumors derived from astrocytes. They can have narrow or diffuse zones of infiltration.

WHO Grading System for Astrocytomas

• WHO Grade 1 — pilocytic astrocytoma
• WHO Grade 2 — astrocytoma
• WHO Grade 3 — anaplastic (malignant) astrocytoma
• WHO Grade 4 — glioblastoma multiforme (most common)

The prognosis is worst for Grade 4 gliomas, with an average survival time of 14-18 months. Overall, the five year survival rate is 5%.