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What is a Posterior Fossa Tumor?

Found near the brain stem and cerebellum, the posterior fossa is a small space in the skull. If a tumor grows in this area, it can partially or completely block the flow of spinal fluid and cause increased pressure on the brain and spinal cord. Because of their proximity to the cerebrum, which controls movement, posterior fossa tumors can be very serious. The physicians at the Florida Hospital Brain and Spinal Cancer Program will monitor these tumors closely. Emergency surgery may need to be performed to address the posterior fossa tumor. To learn more about treatment for posterior fossa tumors, or to schedule an appointment, please call (407) 303-1700 or click here to fill out an online assistance form.

Common types of posterior fossa tumors include:

  • Primary neuroectodermal (new-ro-eck-toe-der-mal) tumors: This type of tumor, often called PNET for short, include medulloepitheliomas, pigmented medulloblastomas, ependymoblastomas, pineoblastomas, and cerebral neuroblastomas.
  • Medulloblastoma (med-dull-oh-blast-toe-mah): Often described as a separate form of posterior fossa tumor, medulloblastoma is actually a type of PNET. More common in children, it accounts for only 1% of adult cancer diagnoses.
  • Hemangioblastoma (he-man-gee-oh-blast-toe-mah): Believed to be associated with von Hippel-Lindau disease, hemangioblastomas account for 7-12% of all posterior fossa tumors. This type of tumor is most often found in patients between the ages of 30 and 40. Men are more likely to be diagnosed with it than women.
  • Metastatic tumors: These tumors begin in other parts of the body, such as the breast, lung, skin or kidney and spread to the brainstem or cerebellum.
  • Schwannoma (shwa-no-mah): Also known as neurilemmoma, this is a benign nerve sheath tumor that involves the Schwann cells. These cells normally produce the sheath that insulates the peripheral nerves. The tumors are relatively slow growing and are almost always benign. Only 1% become malignant, turning into a cancer known as malignant peripheral nerve sheath tumor, malignant schwannoma or neurofibrosarcoma.

Causes of Posterior Fossa Tumors

To understand a posterior fossa tumor, it’s important to know the location inside the brain. The posterior fossa is a small area near the brainstem and cerebellum. The cerebellum is responsible for controlling movement, coordination, and balance. The brainstem controls bodily functions such as breathing. When a posterior fossa tumor develops, it can interfere with the flow of spinal fluid, causing increased pressure on the brain and spinal cord. Currently, the cause of a posterior fossa tumor is unknown, but scientists are working to find more evidence as to why these tumors are created. To learn more about posterior fossa tumors, or to schedule an appointment, please call (407) 303-1700 or click here to fill out an online assistance form.

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Symptoms of Posterior Fossa Tumors

Signs and symptoms of posterior fossa tumors are caused by pressure exerted on the brain or spinal cord and occur very early. The most common symptoms of posterior fossa tumors are:

  • Drowsiness
  • Headache
  • Imbalance
  • Nausea
  • Uncoordinated walk (ataxia)
  • Vomiting
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Tests to Diagnose a Posterior Fossa Tumor

At Florida Hospital Cancer Institute, our brain cancer and spine cancer specialists will find out as much as they can about the tumor in order to offer a correct diagnosis and treatment plan. A variety of tests may be recommended, starting with your reflexes and the power and feeling in your arms and legs. Blood tests may also be taken in order to assess your general health and to see how well your kidneys are functioning. The following procedures may be used to in order to help your physician make a correct diagnosis:

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.

Stereotactic biopsy
Your physician will remove a small amount of tissue from the tumor in order to give a correct diagnosis. In most cases this involves an operation. One of our skilled neurosurgeons will make a very small hole in the skull and pass a fine needle into the tumor in order to remove a small sample. A CT scan will be performed at the same time in order to help guide the surgeon. Your physician will tell you whether or not a biopsy is necessary in your case and what the operation will involve.

Open brain surgery, called a posterior craniotomy

To learn more about tests to diagnose a posterior fossa 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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Symptoms of a Posterior Fossa Tumor

In most cases, general treatment for a posterior fossa tumor will focus on surgery to remove the tumor, even if it isn’t cancerous. Since there is only a small amount of space inside the posterior fossa, a tumor can easily press against the vital structures, causing pressure and pain. Radiation therapy may also be used after surgery, depending on the size and type of the tumor present. 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 posterior fossa tumors:

Surgery
Radiotherapy
 

To learn more about treatment for a posterior fossa 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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