Primary Brain Tumors
Tumors that begin in brain tissue are known as
primary tumors of the
brain. (Information about secondary brain tumors appears in the following
section.) Primary brain tumors are named according to
the type of cells or the part of the brain in which they begin.
The most common primary brain tumors are
gliomas. They begin in glial
cells. There are many types of gliomas:
Astrocytoma—The
tumor arises from star-shaped glial cells called
astrocytes. In adults,
astrocytomas most often arise in the cerebrum. In children, they occur
in the brain stem, the cerebrum, and the cerebellum. A grade III astrocytoma is sometimes called an anaplastic
astrocytoma. A grade IV astrocytoma is usually called a
glioblastoma multiforme.
Brain
stem glioma—The tumor occurs in the lowest part of
the brain. Brain stem gliomas most often are diagnosed in young children
and middle-aged adults.
Ependymoma—The
tumor arises from cells that line the ventricles or the central canal of
the spinal cord. They are most commonly found in children and
young adults.
Oligodendroglioma—This
rare tumor arises from cells that make the fatty substance that covers
and protects nerves. These tumors usually occur in the
cerebrum. They grow slowly and usually
do not spread into surrounding brain tissue.
They are most common in middle-aged adults.
Some types of brain tumors do not begin in glial cells. The most common
of these are:
Medulloblastoma—This
tumor usually arises in the cerebellum. It is the most common
brain tumor in children. It is sometimes called a
primitive neuroectodermal tumor.
Meningioma—This tumor arises in the meninges. It usually grows slowly.
Schwannoma—A tumor
that arises from a Schwann cell.
These cells line the nerve that controls balance and hearing. This nerve is
in the inner ear. The tumor is also called an acoustic
neuroma.
It occurs most often in adults.
Craniopharyngioma—The
tumor grows at the base of the brain, near the
pituitary gland.
This type of tumor most often occurs in children.
Germ cell tumor of
the brain—The tumor arises from a
germ cell. Most germ cell
tumors that arise in the brain occur in people younger than 30. The
most common type of germ cell tumor of the brain is a
germinoma.
Pineal
region tumor—This
rare brain tumor arises in or near the
pineal
gland. The pineal gland is located between
the cerebrum and the cerebellum.
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