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Pilocytic Astrocytoma

What is pilocytic astrocytoma?

Pilocytic astrocytoma (PA) is a slow-growing type of brain tumor. The term “astro” or "astrocyte" comes from the name of the star-shaped cells from which these tumors develop. Astrocytes are a major type of non-nerve cells in the central nervous system (CNS). The CNS is made up of the brain and spinal cord. Many different types of brain tumors grow from astrocytes. But PA tumors tend to be among the slowest growing. They tend to be found mostly in children and teens.

A tumor is an abnormal growth of cells. Healthcare providers who specialize in examining cells under a microscope are called pathologists. They can grade the tumor, on a scale from I to IV, based on how abnormal the cells look and how fast the tumor is likely to grow and invade other tissues. The cells from a grade I tumor look almost normal and grow slowly. A grade IV tumor grows very quickly. 

PA tumors are grade I and tend to grow very slowly. They usually have well-defined borders. They rarely invade nearby tissues. The cells look almost normal under a microscope. Some healthcare providers consider them to be benign or not cancer because of these features.

PA is a primary CNS tumor. That means that it starts in the brain or spinal cord rather than somewhere else in the body and spreading to the brain. PA most often happens in children and teens, but it can also affect adults. 

Any tumor in the brain may cause problems by pressing against brain tissue. The standard treatment for PA is surgery to remove the tumor, when possible. If the tumor is removed, the outlook is usually good.

What causes PA?

Researchers don’t yet know what causes PA tumors. Healthcare providers also don’t have a clear idea about the risk factors for these tumors. Research has suggested links between some genetic conditions and these tumors.

What are the symptoms of PA?

The symptoms of PA depend on where and how big the tumor is. It may not cause symptoms until it's big enough to press on nearby brain tissue and cause problems.

PA tumors often grow in the cerebellum, near the back of the brain. The cerebellum controls balance and coordination. PA tumors sometimes affect the optic nerve and vision. A PA tumor may also block the normal flow of cerebrospinal fluid (CSF). CSF normally bathes and cushions the brain and spinal cord. As CSF builds up, it causes increased pressure on the brain (intracranial pressure). This may cause: 

  • Seizures 

  • Headache 

  • Nausea and vomiting 

  • Dizziness and balance problems 

  • Trouble walking 

  • Eye problems, like double vision 

  • Mental changes

  • Feeling tired and weak

How is PA diagnosed?

Healthcare providers usually ask about your personal and family medical history, recent symptoms, and past health history. You'll need a physical exam and a nervous system exam. For this, your provider will check your coordination and reflexes. Your provider may ask you to do simple things like walk, touch your finger to your nose, or hold your hands out. Your provider might examine your eyes with a light. If a brain tumor is suspected, imaging scans of your brain, often with a contrast media, will be needed. You may need certain tests and procedures, such as:  

  • MRI. MRIs use radio waves, magnets, and a computer to make detailed images of the inside of your body. For this test, you lie still on a table as it passes through a long, tube-like scanner. If you're not comfortable in small spaces, you may be given medicine to help you relax before the test. A contrast dye may be injected into your blood for this test. It helps outline the structures in your head so they show up more clearly on the scans.

  • CTscan. A CT scan uses a series of X-rays and a computer to create detailed images of the inside of your body. For this test, you lie still on a table as it slowly slides through the center of the ring-shaped CT scanner. The scanner directs a beam of X-rays at your body. A CT scan is painless. A dye might be put into your blood to help get clearer images.

  • Biopsy. A biopsy is the only sure way to know what kind of tumor you have. In a biopsy, a tiny piece of the tumor is taken out and tested in a lab.  

You may first see your primary healthcare provider and then get a referral to a: 

  • Neurologist, a specialist in diagnosing and treating diseases of the brain and spinal cord 

  • Neurosurgeon, a specialist who does brain or spinal cord surgery 

  • Neuro-oncologist, a specialist in brain and spinal cord cancers 

How is PA treated?

The standard treatment for PA tumors is surgery to remove them. If the tumor is in a spot where it can’t be fully removed, radiation therapy and chemotherapy may be used. 

Sometimes radiation therapy is used after surgery. But because PA tumors grow very slowly, your healthcare provider may want to “watch” first to see if the tumor comes back. This is because the risks of the radiation therapy may outweigh the risk of the PA growing back. 

You will talk with your medical team about the best treatment plan for you. You'll likely need ongoing follow-up with your healthcare provider. This may include repeated imaging tests to check for signs that the tumor has come back. It's very important to keep follow-up appointments so that your medical team can watch for any changes. 

In some cases, the PA tumor may block drainage of the CSF from your brain. This, causes CSF to build up in the brain. If this happens, you may need surgery to put a tube (called a shunt) in place to drain excess CSF. After the tumor is removed, CSF can drain the way it should, and this problem goes away.

What are possible complications of PA?

Overall, the outcome is good for most people with PA tumors. Rarely, they might come back after treatment.

Key points about pilocytic astrocytoma

  • PA is a type of brain tumor. It starts in the star-shaped astrocyte cells in your brain. These tumors are generally very slow growing.  

  • They most often occur in children and teens, but sometimes happen in adults.

  • PA tumors are often benign because they seldom invade nearby tissues. 

  • The usual treatment for PA is surgery to remove the tumor, if possible. 

  • People with these tumors tend to have a good outcome after treatment. 

  • It's very important to follow up with your medical team to continue to watch for any changes after treatment.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.

  • Before your visit, write down questions you want answered.

  • Bring someone with you to help you ask questions and remember the answers. Taking notes can help.

  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what side effects you should watch for.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you don't take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your provider if you have questions.

Online Medical Reviewer: Kimberly Stump-Sutliff RN MSN AOCNS
Online Medical Reviewer: Lu Cunningham
Online Medical Reviewer: Richard LoCicero MD
Date Last Reviewed: 2/1/2019
© 2000-2019 The StayWell Company, LLC. 800 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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