Malignant peripheral nerve sheath tumors (MPNSTs) are a type of cancer that affects the cells that make up the protective covering around nerves, called the nerve sheath. These tumors can develop in any part of the body, but they most commonly occur in the arms, legs, trunk, and head and neck regions.

MPNSTs can be difficult to diagnose and treat because they are rare and often grow in or around nerves, which can make them difficult to remove surgically. Symptoms of MPNSTs may vary depending on the location of the tumor and can include pain, weakness, numbness, or tingling in the affected area, as well as a lump or mass that can be felt under the skin.

Risk factors for MPNSTs include:

• Neurofibromatosis type 1 (NF1), a genetic disorder that causes tumors to grow along nerves
• Prior radiation therapy to the affected area
• Other genetic conditions that affect nerve function

Treatment for MPNSTs may involve surgery to remove the tumor, radiation therapy, chemotherapy, or a combination of these approaches. Treatment options may vary depending on the size, location, and extent of the tumor, as well as the overall health and preferences of the patient.

The prognosis for MPNSTs can vary widely depending on factors such as the stage and size of the tumor, the extent of the disease, and the response to treatment. Early diagnosis and prompt treatment are important in improving the chances of successful outcomes.

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

Doctors know that these cancers begin when a cell in the protective lining around a nerve develops an error (mutation) in its DNA. The mutation tells the cell to multiply rapidly and to continue living when other cells would normally die. The accumulating cells form a tumor that can grow to invade nearby tissue or spread to other areas of the body.

Treatment for malignant peripheral nerve sheath tumors often involves:

• Surgery. The goal of surgery is to remove the entire tumor and a small margin of healthy tissue that surrounds it. When that isn't possible, surgeons remove as much of the tumor as they can.
• Depending on the location and size of your malignant peripheral nerve sheath tumor, surgery can cause nerve damage and disability. In the case of tumors that occur in the arms and legs, limb amputation may be necessary.
• In some cases your doctor may recommend radiation before surgery to shrink a tumor. That may make it more likely that the tumor can be removed completely.
• Radiation therapy. Radiation therapy uses powerful beams of energy, such as X-rays and protons, to kill cancer cells. Radiation may be used before surgery to shrink a tumor and make successful surgery more likely. After surgery, radiation therapy may be used to kill any cancer cells that might remain.
• Chemotherapy. Chemotherapy is a drug treatment that uses chemicals to kill cancer cells. If your malignant peripheral nerve sheath tumor has spread to other parts of your body, your doctor may recommend chemotherapy to control your symptoms and slow the growth of the cancer.
• Rehabilitation. After surgery, physical therapists and occupational therapists can help you recover function and mobility lost due to nerve damage or limb amputation.