Abstract: Objective To investigate clinical and pathological features of intra-parotid facial nerve schwannoma. Methods A total of 5 cases of intra-parotid facial nerve schwannoma admitted to the Department of Oral and Maxillofacial Surgery, Affiliated Hospital of Jiangsu University from 2015 to 2020 were collected and reviewed. Patients’ clinical data, imaging data, pathological data, preoperative diagnosis, treatment and postoperative nerve injury were analyzed. Results All patients with intra-parotid facial nerve schwannoma were male (33-70 years old). Clinical manifestations were only painless parotid gland mass with clear boundary, without facial nerve paralysis and other symptoms. Two cases were diagnosed as mixed tumor and 3 cases were diagnosed as adenolymphoma before operation. The treatment method was tumor with involved facial nerve resection and anastomosis in which nerve was jointed end-to-end. Post-operative follow-up showed that the facial nerve function of 4 patients was basically normal, and only one patient had grade Ⅱ (House-Brackmann) facial nerve dysfunction. No recurrent cases and malignant changes were observed during follow-up for 10-72 months. Microscopically, tumor cells were long spindle-shaped and arranged in a braided pattern. Immunohistochemistry showed diffuse strong positive expression of S-100 protein in the nuclei and cytoplasm of 5 patients. Also Vimentin was strongly positive in cytoplasm in all 5 cases. Sox10 was positive in the nuclei of 4 cases. Focal expression of CK7 was found in 3 patients. The positive index of Ki-67, a marker of cell proliferation, was less than 3%, and AE1, EMA, P63 and SMA were negative in all cases. Conclusion Clinical manifestations and auxiliary examination of intra-parotid facial nerve schwannoma are non-specific. Preoperative diagnosis is difficult and depends on tissue pathological diagnosis. S-100 and Vimentin could assist the diagnosis of intra-parotid facial nerve schwannoma.

Key words: parotid gland, neurinoma, facial nerve, S-100, Vimentin