被膜内摘出術を行った耳下腺内顔面神経鞘腫例

Abstract

Intraparotid facial nerve schwannoma, an uncommon tumor documented sporadically in medical literature, must be differentiated from pleomorphic adenoma. Function-preserving surgical resection is also important. We report a case of intraparotid facial nerve schwannoma in a 42 year-old woman seen for a right parotid gland tumor 28 mm in diameter. Computed tomography (CT) and Magnetic resonance imaging (MRI) showed a noninvasive round mass between the tip of the mastoid process and the mandibular condyloid process. Fine-needle aspiration cytology confirmed a benign mass consisting of histiocytes or interstitial cells, although preoperative tests could not differentiate schwannoma from pleomorphic adenoma. Surgical exploration found a yellow encapsulated mass arising in the main facial nerve trunk and the nerve funiculus extending into the capsule. A surgeon diagnosed a facial neurogenic tumor, which was resected intracapsularly leaving no tumor tissue in surgical microscopy. Postoperative facial palsy eventually disappeared, completely restoring facial nerve function. No recurrence has been seen in the 7 years and 8 months since surgery, indicating that intracapsular resection may be an intraparotid schwannoma treatment providing a favorable prognosis.