Pilocytic Astrocytoma

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.


What is a pilocytic astrocytoma?

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.

How common is a pilocytic astrocytoma?

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 and Causes

What are the symptoms of a pilocytic astrocytoma?

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.

Where does a pilocytic astrocytoma grow?

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:

What causes a pilocytic astrocytoma?

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:

  • Genetic changes (BRAF gene).
  • Exposure to ionizing radiation during treatment for other cancers like leukemia or lymphoma.

In addition, PA my occur in some genetic conditions, such as:


What are the complications of a pilocytic astrocytoma?

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.

Diagnosis and Tests

How is a pilocytic astrocytoma diagnosed?

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.

Pilocytic astrocytoma radiology

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.


Management and Treatment

How is a pilocytic astrocytoma treated?

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.

Are there side effects of the treatment?

Side effects of surgery to remove the pilocytic astrocytoma tumor may include:

  • Bleeding.
  • Infection.
  • Swelling.
  • Pain.
  • Headaches.
  • Hydrocephalus (a buildup of fluid in the brain).

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:

  • Fatigue.
  • Nausea and vomiting.
  • Diarrhea.
  • Headaches.
  • Hair loss.
  • Skin irritation.
  • Reduced appetite.
  • Frequent urination (peeing) or urgency.

How soon after treatment will I feel better?

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.


Can a pilocytic astrocytoma be prevented?

Since researchers don’t have a clear understanding of the causes of pilocytic astrocytomas, there’s no known way to prevent them.

Outlook / Prognosis

What’s the prognosis for a pilocytic astrocytoma?

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.

What is the survival rate for a pilocytic astrocytoma?

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.

Living With

When should I see a healthcare provider?

Contact a healthcare provider if you or your child experiences symptoms of a pilocytic astrocytoma, like:

  • Headaches.
  • Vision changes.
  • Personality changes.
  • Loss of coordination.

Let your provider know if you or your child experiences any side effects after surgery to remove the tumor, like:

  • Severe pain.
  • Swelling.
  • Color changes to your skin around the incision site.

If something doesn’t seem right, talk to a provider.

What questions should I ask my healthcare provider?

Questions you can ask your provider include:

  • Do I need surgery?
  • What are the side effects of treatment?
  • How do I take care of myself (or my child) after surgery?
  • What complications of surgery should I look out for?
  • What’s my outlook?
  • Are there any clinical trials available for my condition?

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.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 09/27/2023.

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