Recurrent benign pleomorphic adenoma of the parotid gland: Facial nerve identification and risk factors for facial nerve paralysis at re-operation

Abstract Objective Surgery for recurrent pleomorphic adenoma of the parotid gland is challenging since there is a considerable risk of facial nerve injury and a high re-recurrence rate. We investigated surgery for recurrent pleomorphic adenoma, focusing on management of the facial nerve. Methods We reviewed 29 patients who underwent surgery for recurrent benign pleomorphic adenoma of the parotid gland at our department between 1999 and 2018. We examined clinicopathologic features and risk factors for facial nerve injury during reoperation. Results Factors associated with difficulty in identifying the main trunk of the facial nerve during surgery were bilobar tumors, multiple tumors, and use of an S-shaped skin incision at the previous operation. When the facial nerve was identified intraoperatively, it could be preserved in 2/3 of patients, while the nerve was only preserved in 1/3 of patients when it was not identified. Factors related to permanent postoperative paralysis included recurrence in the deep lobe or both lobes and multiple tumors. Conclusion The probability of successfully preserving the facial nerve is relatively high if the nerve can be identified during surgery for recurrent pleomorphic adenoma, although intentional resection is necessary in some patients. Factors associated with difficulty in identifying the facial nerve are similar to those related to permanent postoperative paralysis, including bilobar tumors and multiple tumors. In patients with recurrent pleomorphic adenoma, preservation of the facial nerve is difficult, when they may have undergone previous extensive resection or have multiple tumors requiring subtotal or more extensive resection.