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Types of tumors
What
type of tumor
a brain tumor is depends on where it started, how fast it grows, and whether or not it contains cancer cells. A tumor that begins in the brain or adjacent tissue is called a
primary brain tumor.
These are named for the type of cells in which they begin. For instance, tumors that start in the glial cells are called gliomas. A
secondary brain tumor,
which has spread from another part of the body
,
has the same kind of abnormal cells and the same name as the primary cancer.
Common benign
primary brain tumors
include those of the lining of the skull (meningiomas), those of the nerves (schwannomas), and those of the pituitary gland (pituitary adenomas). However, benign brain tumors can become malignant and, once removed, can also grow back unless nearly every tumor cell was destroyed or removed during treatment.
With few exceptions, most primary brain tumors involving the
brain tissue (gliomas)
are cancerous. These cancers can range from slow-growing, noninvasive tumors
(low-grade tumors)
to rapidly growing, highly destructive tumors
(high-grade tumors)
, such as
glioblastomas.
(Grading is based on the tumor's tendency to spread as well as its growth rate). In the past, low-grade tumors were often referred to as being benign. It is now widely recognized that even these low-grade tumors are rarely cured and usually change into higher-grade tumors over time.
Brain tumors in children often arise from tissues that are different from those most commonly affected in adults. Common
pediatric tumors
include tumors of primitive cells that have not matured into adult cell types
(primitive neuroectodermal tumors or PNETs)
, tumors of the lining of the brain's fluid sacs
(ependymomas)
, and benign tumors of the supporting cells of the brain
(juvenile astrocytomas)
.
This section discusses in more detail:
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