Are Facial Nerve Schwannomas Malignant?
No, facial nerve schwannomas are benign tumors that arise from the Schwann cells of the facial nerve sheath and are not malignant. 1, 2, 3
Nature of Facial Nerve Schwannomas
Facial nerve schwannomas are slow-growing, benign, encapsulated nerve-sheath tumors that can occur in any segment of the facial nerve, from the pontocerebellar angle to the terminal branches. 1, 2
These tumors are rare and represent a distinct entity from the more common vestibular schwannomas, though they can clinically and radiographically mimic vestibular schwannomas when extending into the cerebellopontine angle. 1
Approximately 71% of facial nerve schwannomas are intratemporal in location. 4
Key Clinical Characteristics
The tumors typically grow eccentrically, pushing on nerve fibers rather than infiltrating them, which explains why facial nerve function is often preserved despite tumor presence. 2
Peripheral facial paralysis occurs in only 20-27% of cases at presentation, with many patients remaining asymptomatic or having only mild symptoms. 2
The tumors can present with progressive or acute facial nerve palsy, and may be associated with otological symptoms such as conductive and/or sensorineural hearing loss. 3
Important Distinction from Malignancy
There is no mention in the literature of malignant transformation of facial nerve schwannomas, reinforcing their benign nature. 1, 2, 3, 4, 5
The primary clinical challenge is not malignant potential but rather the risk of facial nerve injury during surgical management, as complete tumor resection typically requires sacrifice of the affected nerve segment. 1
Even with complete surgical resection and nerve grafting, patients can expect no better than House-Brackmann grade III facial function postoperatively. 1
Management Implications
Conservative management with observation is recommended for asymptomatic patients with small tumors and preserved facial function, as the benign nature of these tumors does not mandate aggressive intervention. 1, 3
Stereotactic radiosurgery may be an option for smaller symptomatic tumors with good facial function, offering good tumor control while preserving facial nerve function. 1
Surgical resection is indicated for large tumors or patients with facial paralysis, with the decision between total resection with nerve grafting versus subtotal resection depending on preoperative facial function. 1