Neurofibrosarcoma

Neurofibrosarcoma is a rare cancer that grows in the protective covering around nerves. While the disease is uncommon, people with neurofibromatosis type 1 face a much higher risk of developing these aggressive tumors.

peripheral nerve sheath tumor, malignant peripheral nerve sheath tumor, MPNST, malignant schwannoma, soft tissue sarcoma

Table of contents

• What is neurofibrosarcoma?
• Who is at increased risk?
• Symptoms of neurofibrosarcoma
• What causes neurofibrosarcoma?
• How is neurofibrosarcoma diagnosed?
• Understanding staging
• Treatment options

What is neurofibrosarcoma?

Neurofibrosarcoma, also called peripheral nerve sheath tumor or malignant peripheral nerve sheath tumor (MPNST), is a rare type of cancer that forms in the soft tissues surrounding the peripheral nerves. These nerves carry messages between the brain and the rest of the body and help control voluntary movement. The protective covering around these nerves is called a nerve sheath, and when cells in this sheath become cancerous and multiply, they form tumors.^[1]

These tumors are usually found in the arms and legs, though they can grow anywhere in the body including the head, neck, chest, abdomen, pelvis, and back. The tumors can spread extensively along nerve tissue and are considered aggressive because they grow and spread quickly.^[1][6]

Neurofibrosarcoma is very rare. Only about 200 cases are diagnosed each year in the United States. This type of cancer most commonly affects young adults and middle-aged adults, typically people between 20 and 40 years old, though it can also affect older children and teens.^[6][7]

Who is at increased risk?

People with neurofibromatosis type 1 (NF1), also known as von Recklinghausen’s disease, are at much higher risk for developing neurofibrosarcoma. NF1 is a genetic condition in which benign fibrous tumors develop inside nerve tissue. Between 25% and 50% of people with neurofibrosarcoma also have NF1.^[7][13]

If your child has neurofibromatosis, they may be at increased risk for developing neurofibrosarcoma. These tumors occur in up to 16 percent of people with neurofibromatosis. About 8% to 13% of people with NF1 will develop neurofibrosarcoma in their lifetime.^[1][7]

Other risk factors include previous radiation therapy. About 10% of people with neurofibrosarcoma have received radiation therapy for other medical issues. Certain genetic mutations can also turn normal nerve sheath cells into abnormal cells that multiply and create tumors.^[13]

Symptoms of neurofibrosarcoma

Children with neurofibromatosis type 1 are at very high risk of developing these tumors. Because they affect tissue that is elastic and easily moved, peripheral nerve sheath tumors may exist for a long time before they are diagnosed. Many people with neurofibrosarcoma do not have symptoms at first. Later, when the tumor gets larger, symptoms may appear.^[1][7]

The most common symptoms include:

• Painless swelling or a lump that keeps growing
• Pain or soreness from compressed nerves or muscles
• Nerve loss
• Weakness when trying to move the body part that has the tumor
• Limp or difficulty using the arms, legs, feet, or hands
• Tingling sensations

The tumors may be as small as a pea (about 2 centimeters) or as large as a grapefruit (about 10 centimeters).^[13]

What causes neurofibrosarcoma?

The exact cause of neurofibrosarcoma is not entirely understood. However, studies have indicated that genetics may play a role in the formation of all soft tissue sarcomas. Limited studies have shown a possible link between soft tissue sarcomas and other types of cancer.^[1]

The tumors form when the cells that make up the protective covering around nerves grow and divide more than normal. The fact that almost half of cases occur in people with neurofibromatosis type 1 gives scientists important clues about how the disease develops.^[7]

Neurofibrosarcoma can develop in different ways. Some may stem from cells of peripheral nerves, develop on their own without any known cause, or arise from malignant transformation, which means an existing benign tumor changes and becomes cancerous. This transformation can happen with preexisting neurofibromas, which are benign tumors on nerve tissue.^[5]

How is neurofibrosarcoma diagnosed?

In addition to a complete physical exam, a doctor may order several tests to diagnose a peripheral nerve sheath tumor. These tests help doctors see where the tumor is, how big it is, and whether it has spread to other parts of the body.^[1]

Diagnostic tests may include:

• Biopsy: Taking a small sample from the tumor with a needle. An expert called a pathologist will study cells from the sample under the microscope and run other tests to see what kind of tumor it is.
• X-ray: Creating pictures of bones and tissues inside the body
• Magnetic resonance imaging (MRI): Using magnets and radio waves to create detailed images of soft tissues
• Computerized tomography (CT or CAT) scan: Taking multiple X-ray images from different angles to create cross-sectional views
• Bone scan or PET scan: Using special imaging to check if cancer has spread
• Blood tests, including a complete blood count

After all tests are completed, doctors will be able to outline the best treatment options.^[1]

Understanding staging

Once neurofibrosarcoma has been diagnosed, the tumor is given a “stage,” usually stage I, stage II, stage III, or stage IV. This indicates how far the tumor has spread from its original location. The stage helps doctors decide which form of treatment is most appropriate and predicts how the condition is likely to respond to therapy.^[1]

Neurofibrosarcoma may be localized, meaning it has not spread beyond the nerve tissue where it arose, or metastatic, meaning it has spread to other parts of the body. When it spreads, it usually goes to the lungs. However, most often, neurofibrosarcoma remains localized.^[1]

Treatment options

Surgery to remove the entire tumor and nearby tissue is the standard treatment for peripheral nerve sheath tumors. The goal of surgery is to remove the tumor and some of the healthy tissue around it. When that can’t be done, surgeons remove as much of the tumor as they can. Depending on the size and location of the tumor, it may be necessary to remove all or part of a limb. In most cases, a limb-sparing procedure is used to avoid amputation.^[1][11]

Chemotherapy and radiation therapy may be given before surgery to shrink the tumor or after surgery to kill any remaining cancer cells. Chemotherapy uses anti-cancer drugs to destroy cancer cells. It is sometimes used in patients who have a high risk of the cancer coming back or if it has spread to other parts of the body. However, malignant peripheral nerve sheath tumors don’t respond very well to chemotherapy.^[1][14]

Radiation therapy uses high-energy radiation beams to destroy cancer cells. It can be used either before or after surgery. When used before surgery, it aims to reduce the size of the tumor so it can be operated on and removed. Radiotherapy is also very effective when given after surgery, particularly for intermediate and high-grade tumors.^[14]

The five-year survival rate for people with neurofibrosarcoma is between 23% and 69%. How long someone with the disease lives depends on many factors, such as where the tumor is in the body, if the cancer has spread to other parts of the body, and how much of the tumor was removed during surgery.^[7]

After treatment, patients will have regular follow-up appointments for several years. The usual practice includes a chance to discuss symptoms, an examination to look for any signs of the sarcoma returning, and imaging tests to check for recurrence. Neurofibrosarcoma can come back in the same place, which is called local recurrence.^[14]