Introduction to the surgical treatment of parotid masses

  Parotid masses are one of the most common diseases treated in otorhinolaryngology-head and neck surgery, and clinical practice is still exploring how to further functionalize and minimally invasive treatment of all types of parotid masses. I would like to discuss my experience in parotid mass surgery in my department for 20 years and the classical literature as follows.  Benign masses of the parotid gland are mostly mixed adenomas of the parotid gland (pleomorphic adenoma), which can recur and become malignant. This is followed by adenolymphoma (Warthin tumor), which is prone to multiple tumors and can develop bilaterally. Among the malignant tumors of the parotid gland, mucinous epidermoid carcinoma is common, and its highly differentiated type is of low malignancy and has a better prognosis. This is followed by adenoid cystic carcinoma, which is more malignant and has a poorer prognosis.  The classic surgical procedure for parotid masses is superficial parotidectomy. The widespread clinical use of this procedure has significantly reduced the postoperative recurrence rate of parotid tumors, but the routine facial nerve dissection during surgery obviously increases the operation time and the chance of facial nerve injury, and the function of the parotid gland on the operated side is lost after surgery. With the introduction of functional surgical treatment, how to minimize damage and preserve function with complete removal of the tumor is constantly being explored in clinical practice on an evidence-based basis.  In the treatment of parotid masses, our department adopts superficial lobectomy as the basic surgical procedure, and makes micro-adjustments to the preoperative or intraoperative procedure, including incision design, whether to do full or partial facial nerve dissection, and whether to do total parotidectomy or superficial lobectomy, based on preoperative mass imaging and intraoperative rapid pathology results to understand the size, location, nature, and number of masses.  First of all, anatomically, the superficial lobe of the parotid gland accounts for about 80% of the parotid parenchyma, and about 80% of the tumors are located in the lower pole of the parotid gland, while about 90% of the tumors occur in the superficial lobe of the parotid gland, so most of the masses are located in the lower pole of the parotid gland, which creates conditions for local excision of benign parotid masses. In the past 5 years, our department has tried to improve the surgical method for these masses by performing partial excision of parotid masses and superficial lobes, with the lower part of the parotid gland being the main tissue removed, preserving the parotid ducts and most of the healthy parotid tissue during surgery. Some of the small posterior inferior parotid marginal masses did not actively dissect the facial nerve, and the posterior facial vein was found after turning the flap and operated under it.  The observations were summarized as follows: the surgical trauma was significantly reduced, the operation time was shortened, the postoperative results were satisfactory, and the complications such as facial palsy, facial depression deformity, gustatory sweating syndrome (Frey syndrome), earlobe numbness, and postoperative salivary leakage were significantly reduced. Therefore, according to the evaluation of the masses by preoperative ultrasound and enhanced CT, the author believes that it is effective and feasible to perform superficial lobectomy for most benign parotid masses with regular morphology, intact and smooth envelope, demarcated from the surrounding glands, and less than 3 cm in diameter, which takes into account the preservation of parotid function and the aesthetic requirements of the surgical area and significantly reduces the occurrence of various complications while This procedure is effective and feasible, taking into account the functional preservation of the parotid gland and the aesthetic requirements of the surgical area, and significantly reduces the occurrence of various complications while achieving complete excision of the mass without increasing the postoperative tumor recurrence rate.  Secondly, for larger parotid tumors, the surrounding glandular tissues are often compressed and atrophied, and even some of the tumors protrude outside the superficial lobe of the parotid gland, so it is safer and more thorough to choose conventional superficial parotidectomy. For multiple masses (such as multiple tumors, intra-glandular lymphadenitis, etc.), irregularly shaped masses (such as malformation tumors, etc.) and cystic masses (such as hemangiomas and cysts, etc.) in the superficial lobe, superficial lobectomy is a reasonable choice to prevent multiple tumors from being missed, irregularly shaped and cystic masses from being broken or incompletely excised during surgery, while dissecting and protecting the facial nerve. For deep lobe parotid tumors, total parotidectomy with facial nerve dissection is the usual choice.  For malignant tumors of the parotid gland, total parotidectomy with facial nerve dissection is usually chosen. There have been different opinions on whether to perform intraoperative neck dissection or not. It is generally agreed that when parotid cancer is combined with enlarged lymph nodes and metastasis is considered, cervical dissection should be performed. In the past 5 years, our department has treated many cases of mucinous epidermoid carcinoma of the parotid gland, most of which are well differentiated and have not undergone cervical dissection and postoperative radiotherapy, and there is no recurrence in 3-5 years of follow-up. In addition, several cases of squamous cell carcinoma and parotid ductal carcinoma were treated, and total resection of the mass and parotid gland, facial nerve dissection and suprascapular hyoid muscle clearance were performed.