Intraparotid Facial Nerve Schwannoma with Temporal Bone Extension

Abstract

Objective: To present a rare case of facial schwannoma manifesting as a parotid mass and discuss its diagnosis and treatment.Methods: Design: Case Report Setting: Tertiary Government Hospital Patient: OneResults: A 48-year-old female was seen for a 2-year progressive left hemifacial paralysis and a 5-month gradually enlarging left infraauricular mass with episodes of tinnitus but intact hearing and balance. Physical examination showed a left-sided House Brackmann grade VI facial paralysis and a 5 x 4 x 3 cm soft, ill-defined, slightly movable, nontender, left infraauricular mass. Gadolinium-enhanced magnetic resonance imaging revealed a 5 cm heterogeneouslyenhancing lobulated mass centered within the deep lobe of the left parotid gland extending to the left mastoid, with facial nerve involvement. A diagnosis of a facial nerve tumor, probably a schwannoma, was entertained. Pure tone audiometry revealed normal hearing thresholds for both ears with dips at 6-8 KHz on the left. The patient underwent total parotidectomy withfacial nerve tumor resection via transmastoid approach, with simultaneous facial – hypoglossal nerve anastomosis reconstruction. Histopathologic findings confirmed the diagnosis of a schwannoma. Postoperative facial function was Grade VI. Hearing and hypoglossal nerve function were preserved.Conclusion: A progressive hemifacial paralysis of chronic duration with or without the presence of an infra-auricular mass should raise the suspicion of a facial nerve tumor. Gadolinium-enhanced magnetic resonance imaging is valuable since intraparotid facial nerve schwannomas are mostly diagnosed intraoperatively when the neoplasm and the nerve are exposed and determined to be contiguous. The clinician should be aware that not all parotid masses are salivary gland in origin.Keywords: intraparotid facial nerve schwannoma, facial nerve paralysis, parotid mass