Tumor Types: Non Gliomas
Brain Tumors that are not Gliomas
Chordoma
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.
Craniopharyngioma
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.
Medulloblastoma
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.
Meningioma
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.
(This information was written, in part, by Nancy Conn-Levin,
MA. For more detailed information about meningiomas, please contact
nconnlevin@braintrust.org
)
Pineal Tumors
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.
Pituitary Adenoma
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.
Schwannoma
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.
Vascular Tumors
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.
|