What is a Malignant Peripheral Nerve Sheath Tumor?

A malignant peripheral nerve sheath tumor is a cancerous growth that appears in the soft tissue lining of a nerve. It most commonly develops around a long nerve in one of the extremities, though a tumor can also affect a nerve in the chest, abdomen, pelvis, or neck. A person may experience pain and weakness in the area of the growth that gradually worsens over time. A small malignant peripheral nerve sheath tumor can often be removed surgically, but large or multiple tumors may require a combination of surgery, chemotherapy, and radiation in an attempt to shrink them and reduce the chances of cancer spreading to other parts of the body.

Most people who develop nerve sheath tumors have an underlying genetic disorder called neurofibromatosis. The disorder predisposes an individual to nerve problems, including tissue scarring and tumors, though the condition is usually benign. Only a small number of patients ever develop malignancies. If a malignant peripheral nerve sheath tumor is present but neurofibromatosis is not, the underlying cause is usually never determined. Nerve sheath tumors can affect a person of any age, though they are most commonly diagnosed in adult males.

A new, small malignant peripheral nerve sheath tumor may not cause any noticeable symptoms. As the mass grows, it may start to cause occasional sharp pains, tingling sensations, and muscle aches in the region. It might be possible to feel or see a tumor if it develops close to the skin. Symptoms of fatigue and chronic muscle weakness can be indicative of a late-stage tumor that is beginning to metastasize.

A doctor can diagnose a nerve sheath tumor by asking about symptoms, performing genetic tests for neurofibromatosis, and taking imaging scans of the mass. A tissue biopsy is usually needed as well to see if the growth is cancerous or benign. Doctors determine the best course of treatment based on the size, stage, and location of the malignant peripheral nerve sheath tumor.

Small growths in the extremities and easily accessible sites in the torso and neck can often be excised by a surgeon who specializes in this type of surgery. Extreme precautions are taken during surgery to avoid damaging the delicate underlying nerve tissue. Surgery has a high success rate, but accidental damage could lead to a temporary loss of sensation or permanent paralysis in a body part. Radiation treatments and chemotherapy can be beneficial in combating mid- to late-stage nerve sheath cancers. The prognosis is generally good when patients receive early, aggressive treatment.