How are astrocytomas divided?

Astrocytomas are divided under the following grades:

Low grade astrocytomas:

Pilocytic astrocytoma (such as pilomyxoid astrocytoma, pleomorphic xanthoastrocytoma, and subependymal giant cell astrocytoma) Diffuse astrocytoma (such as gemistocytic astrocytoma, protoplasmic astrocytoma, and fibrillary astrocytoma) Oligodendroglial tumor (such as oligodendroglioma) Mixed glioma (such as oligoastrocytoma)

High grade astroctyomas:

Anaplastic astrocytoma Glioblastoma multiforme Anaplastic oligodendroglioma Anaplastic oligoastrocytoma

This answer is based on source information from National Cancer Institute.