Classification<unk> s are classified by cell type, by grade, and by location. By type of cell<unk> s are named according to the specific type of cell with which they share histological features, but not necessarily from which they originate. The main types of<unk>  are: * Ependymomas: ependymal cells * Astrocytomas: astrocytes <unk> oblastoma multiforme is a malignant astrocytoma and the most common primary brain tumor among adults). * Oligodendrogliomas: oligodendrocytes * Brainstem<unk> : develop in the brain stem * Optic nerve<unk> : develop in or around the optic nerve * Mixed<unk> s, such as oligoastrocytomas, contain cells from different types of<unk> a By grade<unk> s are further categorized according to their grade, which is determined by pathologic evaluation of the tumor. The neuropathological evaluation and diagnostics of brain tumor specimens is performed according to WHO Classification of Tumours of the Central Nervous System. Low-grade brain<unk>  in a 28-year-old male. (Taken on 10 July 2007) * Biologically benign<unk> s WHO grade I are comparatively low risk and can be removed surgically depending on their location * Low-grade<unk> s WHO grade II are well-differentiated (not anaplastic); these tend to exhibit benign tendencies and portend a better prognosis for the patient. However, they have a uniform rate of recurrence and increase in grade over time so should be classified as malignant. * High-grade WHO grades III–IV<unk> s 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, under which tumors are graded from I (least advanced disease—best prognosis) to IV (most advanced disease—worst prognosis). By location<unk> s can be classified according to whether they are above or below a membrane in the brain called the tentorium. The tentorium separates the cerebrum (above) from the cerebellum (below). * The supratentorial is above the tentorium, in the cerebrum, and mostly found in adults (70%). * The infratentorial is below the tentorium, in the cerebellum, and mostly found in children (70%). * The pontine tumors are located in the pons of the brainstem. The brainstem has three parts (pons, midbrain, and medulla); the pons controls critical functions such as breathing, making surgery on these extremely dangerous.
Glioma
Gliosis
Glioblastoma
Astrocytoma
Meningioma
Malignant meningioma
Ameloblastoma
Coma