Cerebellar Low-Grade Astrocytoma

Astrocytoma is one of the most common types of brain tumor that can develop in children. It arises from a specific type of cell in the brain, called an astrocyte. Astrocytomas are divided into subgroups based on their grade and their location in the brain. The grade is determined by what the tumor tissue looks like under the microscope. In general, the lower the grade of a tumor, the less aggressive its behavior.

Cerebellar low-grade astrocytomas are grade I or grade II astrocytomas that occur in an area of the brain called the cerebellum. Grade I astrocytomas make up about 80 percent of low-grade cerebellar astrocytomas.

In most cases we do not understand why children develop cerebellar low-grade astrocytomas. There is nothing you could have done to prevent this from happening. There are certain genetic syndromes, such as neurofibromatosis or tuberous sclerosis, that are associated with astrocytomas, but for the majority of children, these tumors occur without identifiable cause.

The cerebellum is located in a region of the brain known as the posterior fossa. It controls movements and balance, so children with cerebellar tumors often have balance and coordination problems.

Children with tumors in the posterior fossa also often have increased pressure in the brain that is caused by build-up of cerebrospinal fluid, called hydrocephalus. Symptoms of increased pressure include headaches, vomiting, increased sleepiness and vision problems.

The symptoms of cerebellar low-grade astrocytoma usually lead to an imaging study of the brain. Sometimes the initial study is a CT scan, but a MRI scan is usually required to determine the exact location of the tumor and its relationship to the normal brain structures.

Most cerebellar astrocytomas occur on one side within the cerebellar hemisphere. Fluid-filled cysts are common features of these tumors.

The mainstay of treatment for low-grade cerebellar astrocytomas is surgery. During surgery, your child’s pediatric neurosurgeon will remove as much of the tumor as possible. Once the tumor is removed, children are often monitored with imaging tests such as MRI, to make sure the tumor does not come back. If the tumor could not be completely removed surgically, or if there is evidence of recurrence, additional treatment is often warranted.

Children with cerebellar low-grade astrocytomas generally have excellent outcomes. Grade I cerebellar astrocytomas have a 10-year progression-free survival of about 80 to 90 percent if the tumor is removed completely with surgery. Grade II astrocytomas are relatively rare in children but carry a worse prognosis. They often recur after surgery, requiring additional treatments such as chemotherapy, radiation or both.

If the tumor recurs, there are multiple options for additional treatment, such as a second surgery, chemotherapy and radiation therapy. Treatment recommendations depend on factors such as the associated risks of another surgery and the child's age.

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Reviewed by health care specialists at UCSF Benioff Children's Hospital.

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