What is a schwannoma?
A schwannoma, also called a neurinoma, is usually a benign tumour of the peripheral nervous system, that usually grows rather slowly. The tumour forms from the Schwann cells that surround the nerve fibres (Schwann's nerve sheath). In a schwannoma, the cells of the schwann nerve sheath multiply and thus form a lump, which is located deep dermally or in the subcutaneous fatty tissue. The larger a schwannoma becomes, the more pain it can cause. In the worst case, it can even lead to paralysis of the affected nerves. If a schwannoma forms in the auditory or vestibular nerve, it is a so-called acoustic neuroma, which is also called vestibular schwannoma.
In general, 8 percent of intracranial and 29 percent of spinal tumours are schwannomas. They usually occur singly and grow very slowly over the years. Often schwannomas form preferentially in the sensory nerves, but can also affect the motor and autonomic nerves less frequently.
What causes a schwannoma?
Most schwannomas occur sporadically. In concrete terms, this means that doctors cannot pinpoint a precise cause for the schwannoma. However, patients with the genetic syndrome neurofibromatosis type 2 (NF-2) have a higher risk of developing a schwannoma . Due to the genetic changes, there is no longer any regulation of cell growth in the nervous system. As a result, the Schwann cells, which act as an insulating sheath for the nerve fibres, multiply uncontrollably.
What types of schwannomas are distinguished?
If a schwannoma has typical microscopic features, it is called conventional. If a schwannoma has less frequent microscopic features, histological subtypes are distinguished, whereby a name is assigned to each subtype. For example, the following subtypes fall under this :
- Ancient schwannoma:are very rare, benign tumours that form from the nerve sheaths of the peripheral nerves. Ancient schwannomas are somewhat more common in women than in men. Ancient schwannomas show a pronounced degenerative change, for example of vessels on and must absolutely be distinguished from malignancy criteria.
- epithelioid schwannoma:this is a rare, malignant (malignant) neurogenic tumour which forms from the Schwann cells.
- melanotic schwannoma: is the most common type of schwannoma and is typical for its polygonal or spindle-shaped and also epithelioid tumour portion.
- plexiform schwannoma:is a well-demarcated and encapsulated schwann cell tumour.
- cellular schwannoma:A cellular schwannoma is characterised by its high cell density.
What are the symptoms of a schwannoma?
A schwannoma usually manifests itself by a severe swelling in the nerve course. When the swelling is palpated, an electrifying sensation is triggered. The larger the tumour, the higher the risk of nerve paralysis.
In general, however, schwannomas differ in terms of their pain frequency and pain intensity depending on the location of the tumour and can cause the following different complaints :
- Numbness,
- Paresthesia, bladder dysfunction,
- Bladder disorders,
- Rectal dysfunction,
- Visual disturbances,
- Headaches
If the nerves of equilibrium are affected by the schwannoma, it can lead to
a hearing loss, ringing in the ears (tinnitus), a progressive
deterioration of hearing and/or a disturbance of equilibrium.
Is a schwannoma dangerous?
Schwannomas are mostly benign tumours. Only in less than 5 percent of all cases can a schwannoma develop into a malignant peripheral nerve sheath tumour, a so-called MPNST. These tumours are usually not only very large, but have also developed over many years and tend to metastasise.
How is a schwannoma diagnosed?
After the clinical examination of the patient, the diagnosis is made using the usual imaging methods, such as a magnetic resonance imaging (MRI). To make a definite diagnosis of schwannoma, a tissue sample (biopsy) is usually taken. Under the microscope, the schwannoma is seen as a combination of spindle cells and Schwann cells, which look very similar to a normal nerve.
How is a schwannoma treated?
A schwannoma is surgically removed (resection) if possible. In benign tumours, careful dissection techniques in most can preserve the patient's nerve function. To remove the schwannoma, the nerve fibre is cut, which is the origin of the tumour. In this way, all other nerve fibres can be preserved. Afterwards, the tumour is examined histopathologically to exclude a possible degeneration.
If surgery cannot be performed, the tumour can also be treated with radiation therapy or chemotherapy. However, these forms of therapy tend to be ineffective, which is why schwannomas, which cause symptoms, are also treated as part of pain therapy .
What is the usual course of a schwannoma?
The course of disease of a schwannoma can manifest itself in different ways . The decisive factors are the age of the patient, his or her symptoms and the type of pathological gene alteration that is responsible for the development of the schwannoma.
If a neurofibromatosis of type 2 (NF2) is present, the first symptoms can already occur in childhood and lead to complications such as paralysis. Although neurofibromatosis type 2 does not degenerate in principle, it can lead to restrictions in the life expectancy of the patient.
In the case of schwannomatosis, i.e. the presence of multiple schwannomas, the affected person often suffers from chronic pain and/or sensory disturbances. A complete cure is currently not possible for either NF2 or schwannomatosis.
What is the prognosis for a schwannoma?
In the case of complete removal of a benign schwannoma, it is rather rare for the tumour to form again (recurrence), which is why the prospects of a complete cure are very good.