Outcomes of Transoral Robotic Surgery for Parapharyngeal Space Salivary Gland Neoplasms

Background: Prestyloid parapharyngeal space neoplasms have been shown to be amenable to transoral resection. Transoral robotic surgery has been reported to be feasible and relevant to allow better visualization and a four-handed approach to the resection. The principle indication for TORS parapharyngeal space resection is salivary gland neoplasms of the prestyloid compartment. To date, only small cohorts of patients have been reported with insignificant follow-up. Although TORS has numerous advantages for the patients, follow-up imaging data are important in the development of this approach. Objective: The aim of this study to evaluate the oncological outcomes of patients treated by TORS for salivary gland neoplasms of the prestyloid space and to analyze the complication rate in this group of patients. Methods: IRB-approved retrospective review of medical records of patients who underwent TORS parapharyngeal space resection was performed. Clinical, imaging, surgical, and pathological data as well as complications and outcomes were analyzed. Results: A total of 43 patients underwent TORS PPS resection. Overall, 26 underwent resection of prestyloid salivary gland neoplasms. Of 26 patients, 23 had benign neoplasms (pleomorphic adenoma, n = 21, monomorphic adenoma, n = 1, and oncocytoma, n = 1) and 3 had malignant tumors, 2 with carcinomaexpleomorphic adenoma, and 1 had mucoepidermoid carcinoma. Overall, 15 patients who had benign pleomorphic adenoma have been followed for a minimum of 2 years with serial MRI. Complication rates have been very low and consist of infrequent would dehiscence, again, early in the series. Only one patient has demonstrated evidence of recurrence and this was a patient treated early in the series. Our general policy is that malignancy is a contraindication to this approach. However, two patients had carcinoma ex pleomorphic adenoma that FNA did not identify prior to surgery. One had only a small part of the tumor that had transformed, and one of these patients had more extensive invasion diagnosed on permanent section histology and underwent a second stage operation with an open approach and flap reconstruction. Conclusion: A series of 26 parapharyngeal salivary gland tumors managed by transoral robotic surgery demonstrates that malignancy was detected in an approximately 11% of cases (3/26). Benign pleomorphic adenoma (21/26) represents 80% of the indications of our salivary group and approximately half of the entire group (21/43). In our group of pleomorphic adenoma with 2 year minimum follow-up, recurrence rate is 6.6% (1/15). Although longer follow-up is required and refinements in technique continue, the results are promising and suggest a valid role for TORS in parapharyngeal space neoplasms.