Glioma classification


 * Associate Editor-In-Chief:

By type of cell
Gliomas are named according to the specific type of cell they most closely resemble. The main types of gliomas are:


 * Ependymomas — ependymal cells
 * Astrocytomas — astrocytes
 * Oligodendrogliomas — oligodendrocytes
 * Mixed gliomas, such as oligoastrocytomas, contain cells from different types of glia.

By grade
Gliomas are further categorized according to their grade, which is determined by pathologic evaluation of the tumor.


 * Low-grade gliomas are well-differentiated (not anaplastic); these are benign and portend a better prognosis for the patient.
 * High-grade gliomas are undifferentiated or anaplastic; these are malignant and carry a worse prognosis.

Of numerous grading systems in use, the most common is the World Health Organization (WHO) grading system for astrocytoma. The WHO system assigns a grade from 1 to 4, with 1 being the least aggressive and 4 being the most aggressive. Various types of astrocytomas are given corresponding WHO grades.


 * WHO grading system for astrocytomas
 * WHO Grade 1 &mdash; e.g., pilocytic astrocytoma
 * WHO Grade 2 &mdash; e.g., diffuse or low-grade astrocytoma
 * WHO Grade 3 &mdash; e.g., anaplastic (malignant) astrocytoma
 * WHO Grade 4 &mdash; glioblastoma multiforme (most common glioma in adults)

The prognosis is the worst for grade 4 gliomas, with an average survival time of 12 months. Overall, few patients survive beyond 3 years.  

By location
The gliomas can also be roughly classified according to their location:


 * infratentorial : mostly in children (70%)
 * supratentorial : mostly in adults (70%)