* Pineal Tumors
* Pituitary Adenoma
* Primitive Neuroectodermal Tumors
* Vascular Tumors
Chordomas, which are more common in people in their 20s and 30s than in other age groups, develop from remnants of the flexible spine-like structure that forms and dissolves early in fetal development and is later replaced by the spinal cord. Although these tumors are often slow-growing, they can metastasize or recur after treatment. They are usually treated with a combination of surgery and radiation therapy.
Craniopharyngiomas occur in the region of the optic nerves and the hypothalamus, a structure near the pituitary gland. Like chordomas, they develop from cells left over from early fetal development. They produce problems with vision and hormonal problems, slowing the child's growth and causing poor regulation of water balance. The benign craniopharyngioma is a tumor that usually affects infants and children, although it sometimes occurs in adults. While only a decade ago it was considered inoperable and rarely curable by surgery, it can now be removed with minimal or no brain damage in many cases because of the precision afforded by the surgical microscope and microsurgical techniques. Occasionally, if this tumor continues to grow and cannot be removed surgically, radiation therapy is also necessary.
Medulloblastomas are the most common primitive neuroectodermal tumor (PNET), representing more than 25% of all childhood brain tumors. They occur in children more often than in adults. Medulloblastoma most often arises in the cerebellum, located in the lower back part of the brain and causes symptoms that include headache, nausea, vomiting and problems with muscle coordination (ataxia). Unlike other primary brain tumors, medulloblastoma has a tendency to spread throughout the nervous system if it remains untreated. In unusual cases, medulloblastomas may spread outside the nervous system, to the lymph nodes, bone marrow, lungs or other parts of the body. In many cases, they are treated with surgery and radiation therapy alone. They are fast-growing tumors, but because they are very sensitive to radiation therapy and chemotherapy they can often be treated effectively.
A meningioma is a common brain tumor that originates from the meninges, the thin membranes or lining that cover the brain and spinal cord. As they grow, meningiomas compress adjacent brain tissue. Meningioma symptoms are often related to this compression of brain tissue, which can also affect cranial nerves and blood vessels. In some cases, meningioma growth can also extend into the bones of the head and face, which may produce visible changes. Meningiomas account for about 27% of all primary brain tumors and tend to affect more women than men. Most meningiomas are considered benign tumors. However, unlike benign tumors elsewhere in the body, benign brain tumors can
sometimes cause disability and may sometimes be life threatening. In many cases meningiomas appear to grow slowly. Other meningiomas grow more rapidly or have sudden growth spurts. There is no way to predict the rate of growth of a meningioma or to know for certain how long a specific tumor was growing before diagnosis. Although most people develop a single meningioma, it is
also possible to have several tumors growing simultaneously in different parts of the brain and spinal cord. Because recurrent tumors cannot be predicted, it is very important for meningioma survivors to receive regular follow up scans as part of their lifetime health care in order to avoid critical care being neglected.
These tumors arise in the region of the pineal gland, a small structure deep within the brain. They account for about 1% of brain tumors, but make up 3% to 8% of the intracranial tumors that occur in children. At least 17 different types of tumors may occur in this area, many of which are benign. The three most common types of pineal region tumors are gliomas, germ cell tumors and pineal cell tumors. Surgery is absolutely necessary to obtain a sample of tumor tissue so the pathologist can confirm a precise histological diagnosis, which is essential in planning the appropriate therapy. Benign pineal tumors can be removed surgically. The germinoma, the most common malignant tumor in this area, can be cured in more than 90% of patients. Other malignant germ cell tumors occurring in this region are treated with chemotherapy followed by radiation therapy. Over the past 5 years, the prognosis for children with pineal tumors has improved dramatically.
The pituitary gland is a small oval structure located at the base of the brain in the center of the head, behind the eyes and optic nerve. It is about the size of a pea but is very important because it secretes several chemical messengers known as hormones, which help control the body's other glands and regulate growth, metabolism, maturation and other essential body processes. A tiny tumor located just next to the gland, pituitary adenomas account for about 10% of brain tumors. Doctors classify pituitary tumors into two groups - secreting and nonsecreting. Secreting tumors release unusually high levels of pituitary hormones, triggering a constellation of symptoms. They are usually much smaller than the gland when they begin to cause symptoms and the symptoms depend on the tumor's size and the kind of hormone the tumor secretes. Prolactin-secreting adenomas affect sexual characteristics and cause impotence in men. Adenomas secreting growth hormone cause acromegaly (abnormal body growth, enlarged facial features, hands and feet) and gigantism (excessive size and stature). The less common adrenocorticotropic hormone-secreting adenoma causes Cushing's disease. Some adenomas secrete a combination of these or other hormones and some secrete none. Almost all adenomas are benign, but their slow expansion compresses normal structures that surround it, suppressing normal pituitary function and sometimes causing headaches or problems with vision. Pituitary adenomas rarely metastasize or spread to other areas of the body. They are removed in an operation using microsurgical techniques, a very successful form of treatment for the majority of patients.
Primitive Neuroectodermal Tumors
Primitive Neuroectodermal Tumors (PNETs) usually affect children and young adults. Their name reflects the belief, held by many scientists, that these tumors spring from primitive cells left over from early development of the nervous system. PNETs are usually very malignant, growing rapidly and spreading easily within the brain and spinal cord. In rare cases, they cause cancer outside the central nervous system. Medulloblastomas are the most common PNET. Other more rare PNETs include neuroblastomas, pineoblastomas, medulloepitheliomas, ependymoblastomas and polar spongioblastomas. Because their malignant cells often spread in a scattered, patchy pattern, PNETs are difficult to remove totally through surgery. Doctors usually remove as much tumor as possible with surgery then prescribe high doses of radiation and, in some cases, chemotherapy.
Schwannomas arise from the cells that form a protective sheath around the body's nerve fibers. They are usually benign and are surgically removed when possible. One of the more common forms of schwannoma affects the eighth cranial nerve, which contains nerve cells important for balance and hearing. Also known as vestibular schwannomas or acoustic neuromas, these tumors may grow on one or both sides of the brain.
These rare, noncancerous tumors arise from the blood vessels of the brain and spinal cord. The most common vascular tumor is the hemangioblastoma, which is linked in a small number of people to a genetic disorder called Von Hippel-Lindau disease. Hemangioblastomas do not usually spread and doctors typically treat them with surgery.
(This information was taken respectively from here)