Title : Misleading appearances: Intraparotid schwannoma
Abstract:
Schwannomas rarely occur in the head and neck region. Intraparotid facial nerve schwannoma is a rare tumor accounting for only 0.2 - 1.5 % of all parotid tumors. 9% of FNS occur in the parotid gland with only 20 % symptomatic.
Methods: 38-year-old male came with complaints of swelling in the left cheek since 1 year, which progressed in size since 5 months associated with pain. Examination showed a 7x8 cm swelling over the left preauricular recess, firm, mobile, curtains signs with peritonsilar fullness and facial nerve paresis, house brackmann grade 2. FNAC showed Pleomorphic adenoma. MRI neck: There is a 5.2x3.6x2.8 cm heterogeneous enhancing mass in the left parotid gland involving the superficial and deep segments with patchy areas of restricted diffusion consistent with neoplasm with tumour extends along the left stylomastoid foramen. Core biopsy: spinal cell neoplasm Immunohistochemistry: S-100 Positive. Frozen section: benign neoplasm HPE: Features suggestive of schwannoma
Results: Patient came with complaints of facial nerve palsy and peritonsilar fullness, which showed the involvement of facial nerve and deep lobe of parotid. A diagnosis of parotid tumour, pleomorphic adenoma, was made, and the patient was planned for parotidectomy, but intraoperatively the parotid appeared normal and tumor was arising from main trunk of facial nerve, for which the patient underwent excision of a schwannoma.
Discussion:
- The majority of swellings in the parotid region are due to parotid tumours.
- Benign tumours arising from the facial nerve within the parotid are rare and challenging to diagnose preoperatively.
- Schwannomas of the facial nerve seldom present with compression symptoms.Schwannoma arising from the facial nerve is a rare condition accounting for 0.2-1.5% of all parotid tumours.
- MRI scan aids in preoperative assessment of such cases.
- Excision along with an intact capsule remains the primary modality of treatment.
Conclusion: Intraparotid facial nerve schwannomas are rare, benign, slow-growing tumours that mimic parotid gland tumours but usually preserve facial nerve function. Preoperative diagnosis is challenging, making surgical excision the only definitive treatment when symptomatic.
