Overview

Malignant peripheral nerve sheath tumors are rare cancers that start in the lining of the nerves. These cancers happen in the nerves that run from the spinal cord into the body, called peripheral nerves. Malignant peripheral nerve sheath tumors used to be called neurofibrosarcomas.

Malignant peripheral nerve sheath tumors can happen anywhere in the body. They mostly occur in the deep tissue of the arms, legs and trunk. They tend to cause pain and weakness where they occur. They might also cause a growing lump or mass.

Surgery is the usual treatment for malignant peripheral nerve sheath tumors. Sometimes, treatment might include radiation therapy and chemotherapy.

Symptoms

Malignant peripheral nerve sheath tumors often cause symptoms that get worse quickly. Symptoms include:

  • Pain where the tumor is growing.
  • Weakness when trying to move the body part that has the tumor.
  • A growing lump of tissue under the skin.

When to see a doctor

Make an appointment with your health care provider if you have ongoing symptoms that worry you. Malignant peripheral nerve sheath tumors are rare, so your provider might first look for more-common causes for your symptoms.

Causes

It's not clear what causes most malignant peripheral nerve sheath tumors.

Experts know that these cancers begin when a cell in the lining around a nerve gets changes in its DNA. A cell's DNA holds the instructions that tell a cell what to do. The changes tell the cells to make more cells quickly. These cells continue to live when healthy cells die as part of their life cycle.

The cells then can form a mass called a tumor. The tumor can grow into and kill healthy body tissue. In time, the cells can spread to other parts of the body.

Risk factors

Factors that increase the risk of malignant peripheral nerve sheath tumors include:

  • Radiation therapy for cancer. A malignant peripheral nerve sheath tumor might occur in the area treated with radiation 10 to 20 years after treatment.
  • Noncancerous nerve tumors. Malignant peripheral nerve sheath tumors can develop from nerve tumors that aren't cancerous, such as neurofibroma.
  • A condition that runs in families. Malignant peripheral nerve sheath tumors occur more often in people with neurofibromatosis 1. This condition increases the risk of tumors in the nerves.
By Mayo Clinic Staff