From the Guidelines
A schwannoma is a benign tumor that develops from Schwann cells, which are specialized cells that form the protective myelin sheath around peripheral nerves, and the most recent and highest quality study 1 suggests that stereotactic radiosurgery (SRS) is a noninvasive treatment with at least equivalent rates of tumor control and hearing preservation as compared to microsurgical resection (MR), with better facial nerve preservation. These tumors typically grow slowly and encapsulate the nerve without invading it. Schwannomas most commonly occur in adults between 20 and 50 years of age and can develop on any peripheral nerve in the body, though they frequently affect cranial nerves (especially the vestibular nerve, causing vestibular schwannomas or acoustic neuromas), spinal nerve roots, or major peripheral nerve trunks. Some key points to consider include:
- Most schwannomas are solitary, but multiple tumors can occur in conditions like neurofibromatosis type 2.
- Symptoms depend on the tumor's location and may include pain, numbness, weakness, or hearing loss if the auditory nerve is affected.
- Treatment typically involves surgical removal when tumors cause symptoms or show significant growth, with radiation therapy as an alternative in some cases, and according to 1, SRS is an effective treatment in achieving tumor control with similar rates of hearing preservation as compared to conservative surveillance (CS).
- The prognosis is generally excellent as these tumors rarely become malignant, and complete surgical removal usually prevents recurrence, as noted in 1 and 1.
From the Research
Definition of Schwannoma
- A schwannoma is a type of benign nerve sheath tumor arising from the Schwann cell 2, 3, 4, 5, 6.
- It is characterized by a slow-growing and non-infiltrating pattern 3.
- Schwannomas are encapsulated, usually benign, tumors composed of well-differentiated Schwann cells, arising from the neural sheath of peripheral nerves 4.
Types and Locations of Schwannoma
- The most common type of benign schwannoma is the acoustic neuroma arising from the eighth cranial nerve 4.
- Retroperitoneal schwannomas account for 0.5-3% of the retroperitoneal tumors in most series 4.
- Schwannomas can occur in various locations, including the head and neck 2, upper extremities 3, pelvic region 4, 6, and jaw 5.
Diagnosis and Treatment of Schwannoma
- The diagnosis of schwannoma is suggested by clinical features and supported by investigations such as fine needle aspiration cytology (FNAC) and imaging studies (computed tomography or magnetic resonance imaging) 2.
- Magnetic resonance imaging (MRI) is the investigation of choice in the diagnosis of schwannoma and the identification of the nerve of origin 2.
- Complete removal of the tumor is the treatment of choice, and care should be taken to protect the nerve during surgery 3, 5, 6.
- Recidivism and malignant transformation, although rare after surgery, impose postoperative clinical monitoring and annual CT scanning 6.