Florida Hospital Cancer Institute ›› Cancer Programs ›› Brain Cancer & Spine Cancer ›› Conditions ›› Peripheral Nerve Sheath Tumor (PNST)

What is a Peripheral Nerve Sheath Tumor (PNST)?

Peripheral nerves receive messages from the central nervous system (the brain and spinal cord) that stimulate voluntary movement. Peripheral nerve sheath tumors can develop along any of these nerves in the head or neck or arise on the nerves before they exit the skull. They can also grow along the length of the nerve outside the skull, which can cause the nerve to malfunction. To learn more about a peripheral nerve sheath tumor, or to schedule an appointment, please call (407) 303-1700 or click here to fill out an online assistance form.

Doctors at the Florida Hospital Brain and Spinal Cancer Program treat the two most common forms of peripheral nerve sheath tumors (PNST). These types of PNST are almost always benign. Less than 1% are malignant.

  • Neurofibroma (new-roh-fi-bro-mah): Usually found in individuals who have neurofibromatosis type 1, a genetically inherited disease, these nerve sheath tumors can cause physical disfiguration along with pain and even disability. In contrast to schwannomas (another type of tumor originating in the Schwann cells), neurofibromas incorporate many additional types of cells and structural elements into them. This not only makes them difficult to identify, but hard to determine how they originate or develop in the first place.
  • Acoustic neuroma (acoustic new-roh-mah): Also known as vestibular schwannoma, this tumor originates in the Schwann cells, which are responsible for the myelin sheath in the peripheral nervous system. Approximately 3,000 cases are diagnosed in the U.S. each year, accounting for 5-10% of all intracranial neoplasms in adults.

Both of these types of PNST are more often see as slow growing tumors.

Causes of Peripheral Nerve Sheath Tumor (PNST)

Currently, the cause of an peripheral nerve sheath tumors is unknown, but scientists are working to find more evidence as to why these tumors are created. However, there are two types of benign peripheral nerve tumors, schwannomas and neurofibromas,that may be caused by the conditions schwannomatosis and neurofibromatosis. These are inherited conditions that can cause tumors to grow on nerves. 

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Symptoms of Peripheral Nerve Sheath Tumor (PNST)

Signs and symptoms of a peripheral nerve sheath tumor may result in few or no symptoms at all. However, as the tumor develops, it will begin to push against the nerves, resulting in pressure and pain. General symptoms may include a thickening or mass of the muscle fibers, numbness, a burning sensation similar to having “pins and needles”, muscle weakness, and dizziness or trouble with balance. 

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Tests to Diagnose Peripheral Nerve Sheath Tumor (PNST)

Our physicians at Florida Hospital Cancer Institute will need to find out as much as they can about the tumor in order to offer a correct diagnosis and treatment plan. This includes knowing the type, position and size. A variety of tests may be recommended, starting with your reflexes and the power and feeling in your arms and legs. Your physician may also check to see if your optic nerve is swollen, which can indicate a rise in pressure in the brain. Blood tests may also be taken in order to assess your general health and to see how well your kidneys are functioning.

The following tests may be ordered to diagnose a peripheral nerve sheath tumor:

CT (computerized tomography) scan
A CT scan takes a series of x-rays that allows the physician to see a three-dimensional picture of the inside of your body. The CT scan is painless and lasts for only a few minutes. Using a small amount of radiation, the scan will be harmless to you and to those around you. An injection of dye is given in order to let the physician see certain areas more clearly. The injection may make you feel warm or hot all over for a few seconds. Be sure to tell your doctor if you have an allergy to iodine or if you have asthma, as this could lead to a more serious reaction.

MRI (Magnetic resonance imaging) scan
An MRI is similar to a CT scan but uses magnetism instead of x-rays to build up a detailed picture of the areas in your body. Before the scan you may be asked to remove any metal belongings, as well as jewelry. An injection of dye may be given into a vein in your arm, helping the images to show up more clearly. During the scan you will lie on a table inside a long cylinder for approximately 30 minutes. The scan is painless but may be slightly uncomfortable. The MRI technician will help make you as comfortable as possible and will give you earplugs or headphones to reduce the noise from the machine.

To learn more about a peripheral nerve sheath tumor, or to schedule an appointment, please call (407) 303-1700 or click here to fill out an online assistance form.

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Treatments for Peripheral Nerve Sheath Tumor (PNST)

Treatment for an peripheral nerve sheath tumor will vary depending on the specific case. As always, if you need more time to consider your options, you can always take more time. All patients are free to choose not to have treatment and our staff will explain what may happen if you decide to not have it. The following treatment options may be recommended for a peripheral nerve sheath tumor.


To learn more about a peripheral nerve sheath tumor, or to schedule an appointment, please call (407) 303-1700 or click here to fill out an online assistance form.

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