Brain Tumors

GLIOMA

A glioma is a type of tumor that starts in the brain or spine. It is called a glioma because it arises from glial cells. The most common site of gliomas is the brain.

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ADENOMA

An adenoma is a benign tumor (-oma) of glandular origin. Adenomas can grow from many organs including the colon, adrenal glands, pituitary gland, thyroid, prostate, etc. Although these growths are benign, over time they may progress to become malignant, at which point they are called adenocarcinomas. Even while benign, they have the potential to cause serious health complications by compressing other structures (mass effect) and by producing large amounts of hormones in an unregulated, non-feedback-dependent manner (paraneoplastic syndrome).

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ASTROCYTOMA

Astrocytomas are a type of neoplasm of the brain. They originate in a particular kind of glial-cells, star-shaped brain cells in the cerebrum called astrocytes. This type of tumor does not usually spread outside the brain and spinal cord and it does not usually affect other organs. Astrocytomas are the most common glioma and can occur in most parts of the brain and occasionally in the spinal cord. Within the astrocytomas, there are two broad classes recognized in literature, those with:

• Narrow zones of infiltration (mostly invasive tumors; e.g., pilocytic astrocytoma, subependymal giant cell astrocytoma, pleomorphic xanthoastrocytoma), that often are clearly outlined on diagnostic images

• Diffuse zones of infiltration (e.g., low-grade astrocytoma, anaplastic astrocytoma, glioblastoma), that share various features, including the ability to arise at any location in the CNS, but with a preference for the cerebral hemispheres; they occur usually in adults; and an intrinsic tendency to progress to more advanced grades.

People can develop astrocytomas at any age. The low-grade type is more often found in children or young adults, while the high-grade type are more prevalent in adults. Astrocytomas in the base of the brain are more common in young people and account for roughly 75%of neuroepithelial tumors.

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CRANIOPHARYNGIOMA

Craniopharyngioma is a type of brain tumor derived from pituitary gland embryonic tissue, that occurs most commonly in children but also in men and women in their 50s and 60s. It arises from nests of odontogenic (tooth-forming) epithelium within the suprasellar/diencephalic region and, therefore, contains deposits of calcium, which are evident on an x-ray. Histologically, craniopharyngiomas resemble adamantinomas (the most common tumors of the tooth). Patients may present with bitemporal inferior quadrantanopia leading to bitemporal hemianopia, as the tumor may compress the optic chiasm. It has a point prevalence of approximately 2/100,000.

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EPENDYMOMA

Ependymoma is a tumor that arises from the ependyma, a tissue of the central nervous system. Usually, in pediatric cases the location is intracranial, while in adults it is spinal. The common location of intracranial ependymoma is the fourth ventricle. Rarely, ependymoma can occur in the pelvic cavity.
Syringomyelia can be caused by an ependymoma. Ependymomas are also seen with neurofibromatosis type II.

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MENINGIOMA

Meningiomas are a diverse set of tumors arising from the meninges, the membranous layers surrounding the central nervous system. According to the American Brain Tumor Association, meningiomas are the most common primary brain tumor, representing one-third of all such tumors. They arise from the arachnoid "cap" cells of the arachnoid villi in the meninges. These tumors are usually benign in nature; however, a small percentage are malignant. Many meningiomas are asymptomatic, producing no symptoms throughout a person's life, and require no treatment other than periodic observation. Symptomatic meningiomas are typically treated with either radiosurgery or conventional surgery. Historical evidence of meningiomas has been found going back hundreds of thousands of years, with some successful surgeries for their removal beginning in the 1800s.

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OLIGODENDROGLIOMA

Oligodendrogliomas are a type of glioma that are believed to originate from the oligodendrocytes of the brain or from a glial precursor cell. They occur primarily in adults (9.4%of all primary brain and central nervous system tumors) but are also found in children (4%of all primary brain tumors). The average age at diagnosis is 35 years.

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