Neuro-oncologia

Brain tumors that result from transformation and abnormal growth of brain cells are called primary brain tumors because they originate in the brain. Usually they are named after the part of the brain or the type of brain cell from which they arise.

Secondary brain tumors or metastatic tumor occur when cancer cells from other parts of the body, such as the lung, breast, skin, kidney, colon spread to the brain. These tumor cells reach the brain via the blood-stream. Secondary tumors in the brain are far more common than primary brain tumors. About 25% of tumors elsewhere in the body metastasize to the brain.

The WHO classification of tumors of the central nervous systems is the standard for the definition of CNS neoplasms in the clinical oncology and cancer research fields and aims at establishing a nomenclature that is used and accepted worldwide, and at incorporating the latest advances in the field. The fourth edition was published in 2007.

A little bit of history

The first morphologic classification of CNS neoplasms was done by Bailey and Cushing in 1926 (Bailey P, Cushing H. A classification of tumors of the glioma group on a histogenetic basis with a correlation study of prognosis. Philadelphia:Lippincott; 1926.) and morphology is still the mainstay of pathology diagnosis.

	Tumors of neuroepithelial tissue	WHO grade
	Astrocytic tumors
	Subependymal giant cell astrocytoma	Grade I
	Pilocytic astrocytoma	Grade I
	Pilomyxoid astrocytoma	Grade II
	Diffuse astrocytoma	Grade II
	Pleomorphic xanthoastrocytoma	Grade II
	Anaplastic astrocytoma	Grade III
	Glioblastoma	Grade IV
	Giant cell glioblastoma	Grade IV
	Gliosarcoma	Grade IV

	Oligodendroglial tumors
	Oligodendroglioma	Grade II
	Anaplastic oligodendroglioma	Grade III

	Oligoastrocytic tumors
	Oligoastrocytoma	Grade II
	Anaplastic oligoastrocytoma	Grade III

	Ependymal tumors
	Subependymoma	Grade I
	Myxopapillary ependymoma	Grade I
	Ependymoma	Grade II
	Anaplastic ependymoma	Grade III

	Choroid plexus tumors
	Choroid plexus papilloma	Grade I
	Atypical choroid plexus papilloma	Grade II
	Choroid plexus carcinoma	Grade III

	Other neuroepithelial tumors
	Angiocentric glioma	Grade I
	Chordoid glioma of the third ventricle	Grade II

	Neuronal and mixed neuronal–glial tumors
	Gangliocytoma	Grade I
	Ganglioglioma	Grade I
	Anaplastic ganglioglioma	Grade III
	Desmoplastic infantile astrocytoma and ganglioglioma	Grade I
	Dysembryoplastic neuroepithelial tumor	Grade I
	Central neurocytoma and extraventricular neurocytoma	Grade II
	Cerebellar liponeurocytoma	Grade I
	Paraganglioma of the spinal cord	Grade I
	Papillary glioneuronal tumor	Grade I
	Rosette-forming glioneuronal tumor of the fourth ventricle	Grade I

	Pineal tumors
	Pineocytoma	Grade I
	Pineal parenchymal tumor of intermediate differentiation	Grade II
	Pineoblastoma	Grade IV
	Papillary tumor of the pineal region	Grade II or III

	Embryonal tumors
	Medulloblastoma	Grade IV
	CNS primitive neuroectodermal tumor (PNET)	Grade IV
	Atypical teratoid/rhabdoid tumor	Grade IV

	Tumors of the cranial and paraspinal nerves
	Schwannoma	Grade I
	Neurofibroma	Grade I
	Perineurioma	Grade I
	Malignant peripheral nerve sheath tumor (MPNST)	Grade II, III or IV

	Meningeal tumors
	Meningioma	Grade I
	Atypical meningioma	Grade II
	Anaplastic meningioma	Grade III
	Hemangiopericytoma	Grade II
	Anaplastic hemangiopericytoma	Grade III
	Hemangioblastoma	Grade I

	Tumors of the sellar region
	Craniopharyngioma	Grade I
	Granular cell tumor of the neurohypophysis	Grade I
	Pituicytoma	Grade I
	Spindle cell oncocytoma of the adenohypophysis	Grade I

References:

- Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, Burger PC, Jouvet A, Scheithauer BW, Kleihues P. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol. 2007 Aug;114(2):97-109. Epub 2007 Jul 6. Review. Erratum in: Acta Neuropathol. 2007 Nov;114(5):547.