Brain tumor classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Overview[edit | edit source]

Brain tumors can be classified into two main categories: primary and secondary tumors. Primary tumors originate in astrocytes, oligodendrocytes and ependymal cells. Secondary tumors originate in malignant cancers located primarily in other organs. Brain tumors are classified depending on location of the tumor, type of tissue involved and whether they are benign or malignant.

Classification[edit | edit source]

Primary tumors[edit | edit source]

Tumors occurring in the brain include:

• Astrocytoma
• Pilocytic astrocytoma
• Dysembryoplastic neuroepithelial tumor
• Oligodendrogliomas
• Ependymoma
• Glioblastoma multiforme
• Mixed gliomas
• Oligoastrocytomas
• Medulloblastoma
• Retinoblastoma
• Neuroblastoma
• Germinoma
• Teratoma

Most primary brain tumors originate from glia (gliomas) such as astrocytes (astrocytomas), oligodendrocytes (oligodendrogliomas), or ependymal cells (ependymoma). There are also mixed forms, with both an astrocytic and an oligodendroglial cell component. These are called mixed gliomas or oligoastrocytomas. Plus, mixed glio-neuronal tumors (tumors displaying a neuronal, as well as a glial component, e.g. gangliogliomas, disembryoplastic neuroepithelial tumors) and tumors originating from neuronal cells (e.g. gangliocytoma, central gangliocytoma) can also be encountered.

Other origins of primary brain tumors include: primitive neuroectodermal tumors (PNET, e.g. medulloblastoma, medulloepithelioma, neuroblastoma, retinoblastoma, ependymoblastoma), tumors of the pineal parenchyma (e.g. pineocytoma, pineoblastoma), ependymal cell tumors, choroid plexus tumors, neuroepithelial tumors of uncertain origin (e.g. gliomatosis cerebri, astroblastoma), etc.

Secondary tumors and non-tumor lesions[edit | edit source]

Secondary or metastatic brain tumors originate from malignant tumors (cancers) located primarily in other organs. Their incidence is higher than that of primary brain tumors. These tumor cells reach the brain via the blood-stream. The most frequent types of metastatic brain tumors are:

• Lung cancer
• Skin cancer
• Malignant melanoma
• Hypernephroma
• Breast cancer
• Colon carcinoma

Some non-tumoral masses and lesions can mimic tumors of the central nervous system. These include:

• Tuberculosis of the brain
• Cerebral abscess (commonly in toxoplasmosis)
• Hamartomas (for example, in tuberous sclerosis)
• Von Recklinghausen neurofibromatosis

References[edit | edit source]

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