Astrocytoma, a tumor consisting of astrocytes, is the most common form of primary brain tumors.

Astrocytomas are classified based on their rate of growth.

Grade/astrocytotomas grow slowly, whereas grade IV astrocytomas are highly malignant.
- Astrocytes are longer and bigger than microglia and are vascularized.
- Tumours of astrocytes are called astrocytomas
- These are one of the hardest tumours because they continuously bleed.