Locations:
Pilocytic astrocytoma is a central nervous system tumor made up of star-shaped cells in your brain. It most often affects children and adults before age 20. This tumor is low-grade, which means it’s treatable and leads to a good prognosis if detected early. Removal surgery can cure this tumor.
Pilocytic astrocytoma (PA) is a brain tumor made up of astrocyte cells. Astrocytes are star-shaped cells that support signal-transmitting neurons (nerve cells) in your brain to help it function.
The World Health Organization classifies PA as a grade I, nonmalignant tumor. Grade 1 means that the tumor cells look like normal (noncancerous) cells under a microscope, and they grow slowly. It usually doesn’t spread to other parts of your body, but the tumor itself can grow large. Surgically removing the tumor cures the condition.
Pilocytic astrocytoma tumors are the most common brain tumors among children. They affect an estimated 1 out of every 100,000 people before age 20 in the United States. PA makes up about 15% of all brain tumors among children and approximately 5% of all brain tumors among adults.
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Symptoms of pilocytic astrocytoma vary based on the size and location of the tumor. In some cases, you might not experience any symptoms until the size of the tumor increases. Symptoms could include:
Seizures aren’t common, but they’re possible.
Most pilocytic astrocytoma tumors grow in your central nervous system (brain and spinal cord). The most common location is in your cerebellum. This is the lower part of your brain at the back of your head where your head meets your neck.
Other less common locations of a PA tumor include your:
An overgrowth of astrocyte cells causes pilocytic astrocytoma. We’re not sure of the exact reason why this happens. Studies show this tumor could develop due to:
In addition, PA my occur in some genetic conditions, such as:
Complications of pilocytic astrocytoma may include:
Among rare and severe cases, the location and size of the tumor can cause brainstem compression (pressure against your brainstem) or hydrocephalus (fluid buildup in your brain). These can be life-threatening.
A healthcare provider will diagnose pilocytic astrocytoma after a physical exam and testing. They’ll learn more about your symptoms during the exam, along with your medical history. Testing can help your healthcare provider rule out conditions with similar symptoms. Tests are usually noninvasive imaging tests to find the tumor in your central nervous system.
An imaging test, most often magnetic resonance imaging (MRI), reveals the tumor and leads to a pilocytic astrocytoma diagnosis. Sometimes, children who experience neurological symptoms have trouble undergoing an MRI. During these cases, a healthcare provider will recommend another imaging test (a CT scan) to make it easier on the child. Imaging tests can identify the size, shape and location of the tumor. This can help your healthcare provider plan for treatment.
The treatment providers recommend for pilocytic astrocytoma is surgical removal of the tumor. Surgery can cure PA if it’s possible to completely remove the tumor this way. Sometimes, the size and location of the tumor make removal difficult. If there’s a high risk of complications, your surgeon may only remove a portion of the tumor and then monitor its size and growth over time. If the tumor grows or comes back after removal, additional surgery may help.
A less common form of treatment is radiation therapy. Your provider may choose this based on tumor location, and other available surgical or chemotherapy options. Your healthcare provider will choose a form of treatment that’s best for you.
With the advancement of genetic testing — also known as molecular testing for PA — this test, done after surgery, can detect some mutations that lead to symptoms, like BRAF v600E. There are FDA-approved therapies that your provider can prescribe as a form of treatment for PA. In addition, you may be eligible for experimental therapies or clinical trials. These may offer a benefit to you and others. Talk to your provider about molecular testing from tumor tissue after surgery.
Side effects of surgery to remove the pilocytic astrocytoma tumor may include:
Your surgeon will discuss these side effects before treatment. They’ll also take extreme care to prevent any side effects or complications during the procedure.
Side effects of radiation therapy may include:
It could take several weeks for your body to heal after surgery to remove the pilocytic astrocytoma tumor. Your provider will give you instructions so you can take care of yourself or your child after surgery. Let your provider know if you have any questions.
Since researchers don’t have a clear understanding of the causes of pilocytic astrocytomas, there’s no known way to prevent them.
For a grade 1 pilocytic astrocytoma, your prognosis (outlook) is excellent. The tumor is nonmalignant (not cancerous) and usually doesn’t spread to other parts of your body. Your outlook is best if a healthcare provider finds and treats the tumor early. Your prognosis also varies based on your general health, age and other factors at the time of a diagnosis. A healthcare provider can give you a detailed outlook based on your situation.
The life expectancy for children and adults who receive a pilocytic astrocytoma diagnosis before age 20 is very high. One study found that the 10-year survival rate was above 92%. The survival rate further increases if surgeons are able to completely remove the tumor.
Contact a healthcare provider if you or your child experiences symptoms of a pilocytic astrocytoma, like:
Let your provider know if you or your child experiences any side effects after surgery to remove the tumor, like:
If something doesn’t seem right, talk to a provider.
Questions you can ask your provider include:
A note from Cleveland Clinic
It can be stressful and scary to learn that you, your child or a loved one has a brain tumor. A pilocytic astrocytoma is a treatable tumor that leads to a good prognosis. It doesn’t usually spread to other parts of your body, and removing the tumor can cure it. Your care team will help you find the right treatment plan to remove the tumor. They’ll also use caution to prevent complications so you can feel better.
Last reviewed by a Cleveland Clinic medical professional on 09/27/2023.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy