What Is Pilocytic Astrocytoma?

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Pilocytic astrocytoma (PA) is a slow-growing tumor that originates from star-shaped cells called astrocytes in the brain or spinal cord. Astrocytes are a kind of glial cell, cells that support and nourish neurons in the brain.

PA occurs mostly in children and young adults under age 20. They are relatively benign tumors and have a 10-year survival of over 90%.

In this article, the symptoms, causes, diagnosis, and treatment of pilocytic astrocytoma will be explored.

neurosurgeon checking mri scans

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Pilocytic Astrocytoma Symptoms

The symptoms of PA depend on where the tumor is and its size. PA can arise anywhere in the central nervous system but typically develops near the cerebellum, brain stem, hypothalamic region, or optic nerve.

PA in the brain may not cause symptoms until it's big enough to press on nearby brain tissue and increase intracranial pressure, a rise in pressure inside the skull. This may cause:

  • Seizures that aren't linked to fever
  • Headache 
  • Nausea and vomiting 
  • Dizziness
  • Trouble walking and balance problems 
  • Eye problems, like double vision 
  • Behavior or personality changes
  • Delays in development
  • Feeling tired and weak

Astrocytomas that occur in the spinal cord can cause weakness and disability in the area affected by the growing tumor.

Many of these changes can be caused by other medical problems. Still, it's important to see a healthcare provider if you notice these symptoms in your child.

Causes

The exact cause of PA is unknown.

Astrocytomas occur with greater frequency with certain genetic disorders. These conditions include:

  • Neurofibromatosis types 1 and 2: A genetic disorder that causes tumors to grow in nervous system tissue.
  • Li-Fraumeni syndrome: A mutation of a tumor suppression gene known as TP53, which increases the risk of tumor growth throughout the body.
  • Tuberous sclerosis: A genetic disease that causes benign tumors to grow in the brain and other vital organs, including the kidneys, heart, eyes, and lungs.
  • Turcot syndrome: A rare genetic disorder that causes benign (noncancerous) growths to form in the brain and colon.

Diagnosis

Diagnosis starts with a comprehensive review of your child’s medical history and assessments of physical and neurological health. 

For this, your healthcare provider will check coordination and reflexes. The doctor may ask your child to do simple things like walk, touch their finger to their nose, or hold their hands out. The provider might also use a light to examine their eyes.

If a brain tumor is suspected, imaging scans of the brain will be carried out. Some of the tests and procedures needed include:  

  • Magnetic resonance imaging (MRI) scan: MRIs use radio waves, magnets, and a computer to make detailed images inside the body. MRI is the best test to look for tumors in the central nervous system (the brain and spinal cord).
  • Computed tomography (CT) scan: A CT scan uses a series of X-rays and a computer to create detailed images inside the body. CT and MRI scans are usually done with injected contrast material, which is fluid that surrounds solid areas, such as brain tumors, to better define the edges. 
  • Biopsy: A biopsy might be the only sure way to know what kind of tumor it is. But sometimes PA can be diagnosed based on how it looks on imaging tests. In a biopsy, a tiny piece of the tumor is removed. To take a sample, a surgeon makes a small hole in the skull and inserts a hollow needle into the brain. When possible, the entire tumor will be removed during the procedure.

The tissue removed during a biopsy is sent to a lab for testing. Part of the testing includes finding the tumor's grade. The grade tells how different the tumor cells are from normal cells and how fast they're likely going to grow and spread. Low-grade brain tumors are considered less aggressive than high-grade ones.

Most PAs develop within the first two decades of life and are the most common cerebellar tumor in children. The incidence rate is estimated at 14 new cases per million in children younger than 15 years of age. Most astrocytomas (approximately 80%) in children are low grade.

Treatment

In some cases, no treatment is required. For example, if the tumor is slow growing and not causing any symptoms. A doctor will monitor the tumor with regular MRI scans to make sure it doesn’t grow larger.

When the tumor is causing symptoms, treatments include surgery, chemotherapy, and radiation therapy.

Surgery

If the PA is causing symptoms or a scan shows that the tumor is growing, a doctor may advise treatment.

The main form of treatment for a PA is surgical excision and removal of as much of the tumor as possible (resection). With cerebellar tumors, most cases can be completely removed by surgery, which is generally considered curative.

In some cases, only a portion of the tumor can be safely removed. In such cases, follow-up (adjuvant) therapy is necessary with either certain anticancer drugs (chemotherapy) or radiation therapy. 

Radiation Therapy

If the tumor is in a spot where it can’t be fully removed during surgery and is causing problematic symptoms, adults and older children might get radiation therapy, which uses high doses of radiation to help kill any tumor cells left in the area. Sometimes chemotherapy is used. 

In younger children, chemotherapy might be recommended after surgery, but radiotherapy is rarely used. This is because radiation can cause long-term growth and developmental problems in young children.

Prognosis

PA has an excellent prognosis. Effective treatments have led to very high cure rates of around 96%, which is one of the highest survival rates of any brain tumor. Recurrence rates are low if the tumor is completely removed, but if the tumor does come back, the prognosis is still excellent after a second surgery.

Summary

Pilocytic astrocytoma is a slow-growing tumor that occurs most commonly in people under 20 years old. PA has an excellent prognosis and can often be cured with surgery.

A Word From Verywell

When you hear the words "brain tumor," you may automatically think the worst. But if your child is diagnosed with pilocytic astrocytoma, know that with treatment, this condition has an excellent prognosis. Lean on your healthcare team to answer any questions you have and for support as you care for your child throughout their treatment.

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5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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