Clinical Retrospective Analysis of 9 Cases of Intraparotid Facial Nerve Schwannoma

The management of intraparotid facial nerve schwannoma (IFNS) is challenging because it is extremely rare and often misdiagnosed as pleomorphic adenoma or another parotid tumor. The purpose of this study was to report on the authors' experience in the treatment of IFNS and to review the literature regarding the diagnosis and management of IFNS.

From January 1997 through October 2015, 916 consecutive parotidectomies were performed at Shenzhen People's Hospital (Shenzhen, China). Of 916 parotid tumors samples, 9 cases of IFNS confirmed by histopathology were identified and analyzed retrospectively. In addition, 161 published cases from 1956 through 2015 were systematically reviewed.

Nine cases of IFNS were identified from 916 parotid tumors samples and accounted for 0.98% of all parotid tumors. All these patients with IFNS underwent tumor removal and parotidectomy with preservation of facial nerve (FN) continuity. The mean follow-up period was 6.2 years (range, 1 to 16 yr). Facial function improved gradually from House-Brackmann grade (HBG) II to III immediately postoperatively to HBG I during the subsequent 3 to 9 months in all cases. Tumor recurrence with stylomastoid foramen involvement was observed in 1 case 3 years after surgery. The others remained free of recurrence. Of 161 IFNS cases reported in the literature, 17 cases with facial paresis were found to have intra-temporal involvement, but no facial paresis was found in patients with intraparotid involvement only.

An IFNS is easily misdiagnosed as pleomorphic adenoma or Warthin tumor preoperatively; the correct diagnosis for IFNS depends mainly on intraoperative observation of the gross relation between the tumor and the FN or excision frozen biopsy examination. The integrity of the FN should be preserved for patients with IFNS and without facial paresis, whenever possible.