A schwannoma (sh-won-oma) is a tumour of the tissue that covers nerves, called the nerve sheath. These tumours develop from a type of cell called a Schwann cell, which gives them their name. Schwannomas are often not cancerous (benign). The most common type of benign schwannoma is the acoustic neuroma. This can cause deafness because it grows on a nerve called the 8th cranial nerve, which controls hearing.
When these tumours are cancerous they are called malignant schwannomas. They can start anywhere in the body. The most common areas are
- The major nerve of the leg (the sciatic nerve)
- The nerves at the top of the arm (the brachial plexus)
- The lower back (the network of nerves called the sacral plexus).
Perineal schwannomas have been reported. These grow in the nerves that supply the area between your legs. As well as causing pain, they may affect how your bowel or bladder work.
Malignant schwannomas are also called malignant peripheral nerve sheath tumours (MPNSTs) or neurofibrosarcomas. They are rare tumours that come under the general heading of soft tissue sarcoma. We have a section about soft tissue sarcoma.
Neurofibromatosis is a rare inherited condition, with an even rarer form called schwannomatosis. People with schwannomatosis develop multiple schwannomas on the nerves in their heads, spine and limbs. The main problem they have is pain from the affected nerves. Unlike people with the other types of neurofibromatosis, people with schwannoma don't go deaf and don't have a higher risk of other types of cancer. An American organisation called the Children's Tumor Foundation gives some information about schwannomatosis.
Treatments for MPNST include surgery, radiotherapy and chemotherapy. Because these tumours are so rare, it is difficult to find information about them. One review of 54 patients with this type of nerve tumour treated over the last ten years found that the people likely to do best
- Had tumours smaller than 5cm across
- Were able to have their tumours completely removed
- Tended to be younger rather than older
These tumours don't respond very well to chemotherapy. Chemotherapy may be used to try to shrink the tumour or keep it at bay, but it is unlikely to cure it. The tumours may respond well to radiotherapy.
Non cancerous (benign) schwannomas are usually treated with surgery.
Usually, a schwannoma coming back in the same place means that it wasn't completely removed the first time round. There may have just been microscopic traces of it left behind. This is enough for it to grow into a new tumour. It might happen because your surgeon couldn't remove any more than they did. When this type of tumour comes back, it can be more difficult to treat. You could have surgery again if it is possible to remove the new tumour.
Even though some schwannomas are cancerous, they often grow slowly. If it is possible to remove the tumour when it grows back this could keep the symptoms under control for many years in some people. You may also be able to have radiotherapy again, depending on the dose you had previously.
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