Surgical approach to parotid pleomorphic adenoma: a 15-year retrospective cohort study

Abstract

Our aim was to investigate the clinical outcomes (recurrences, duration of follow-up, and effectiveness) after extracapsular dissection and superficial parotidectomy for pleomorphic adenoma of the parotid gland. We retrospectively studied 261 patients whose adenomas were treated at the Maxillofacial Unit of Magna Graecia University of Catanzaro between January 2003 and December 2015 and had been followed up for at least three years after either extracapsular dissection or superficial parotidectomy. The difference in recurrences and complications between the two techniques were measured by univariate analysis (Fisher’s exact test). The level of significance was set at p ≤ 0.05. Of the 261 patients 125 were male (48%) and 136 female (52%), mean (range) age 47 (14-78) years. A total of 210 of the 261 patients had an extracapsular dissection (80%, 101 male and 109 female), and 51 had a superficial parotidectomy (24 male and 27 female). Postoperative complications were recorded in 48 of the 261 patients; complication rate was 10% in the extracapsular dissection group, and a third after superficial parotidectomy. There were more complications in the parotidectomy group (p=0.042). For pleomorphic adenomas located in the superficial portion of the parotid gland, extracapsular dissection is a viable alternative to traditional superficial parotidectomy in the hands of experienced parotid surgeons with regard to clinical outcomes, and it may be superior with regard to cost.

Introduction

Parotid tumours comprise 1%-3% of all primary head and neck cancers, and 70%-90% have benign histopathological characteristics. Among these benign lesions, pleomorphic adenoma (PA) is the most common (60% of cases), while 20% are cystadenolymphomas and the remaining 20% vary (for example – oncocytomas, monomorphic adenomas, and lymphoepithelial lesions) (Colgan L. Poster 54, presented at the Annual Meeting of the British Association of Oral and Maxillofacial Surgeons, 2011). About 85% of pleomorphic adenomas originate in the superficial lobe, and only 10% are located in the deep lobe. Because of their tendency to local recurrence, appropriate surgical treatment has been the subject of major debate, mainly because of the risks of injury to the facial nerve and capsular rupture, as well as recurrence.

During the last century the surgical treatment of parotid tumours evolved, but there are still controversies among the advocates of broader surgical treatments such as superficial and total parotidectomy, and advocates of more limited treatments like partial parotidectomy and extracapsular dissection. This is because the treatment of benign parotid tumours, particularly pleomorphic adenoma, has gone from being classed as tumour surgery and become surgery for preservation of the facial nerve in a benign tumour.

In our previous study, in which we reported a series of 10 years’ experience, we evaluated the complications found in patients with parotid adenomas treated by superficial parotidectomy compared with patients treated by extracapsular dissection. The objective of the present study was to evaluate the clinical outcomes, in particular recurrences, after a longer follow-up, between patients whose parotid adenomas were treated by extracapsular dissection and those treated by superficial parotidectomy.

Patients and methods

Patients who had a pleomorphic adenoma of the parotid gland treated at the Maxillofacial Unit of Magna Graecia University of Catanzaro between January 2003 and December 2015 and with at least three years’ follow-up were included in this retrospective cohort study. The diagnosis of pleomorphic adenoma was established by ultrasonography (US), computed tomography (CT), or magnetic resonance imaging (MRI) of the head and neck, and fine needle aspiration cytology (FNAC) or aspiration biopsy (FNAB). Patients included in the study had a tumour localised in the superficial portion of the parotid gland with a diameter of 3.0 (0.5) cm on echography, MRI, or CT. Patients were randomised to have either superficial parotidectomy or extracapsular dissection. The study was approved by the appropriate ethics committees, and informed consent was given by patients.

Postoperatively all patients were examined monthly for the first three months, every three months for the first year, and every 12 months for another four years for a total of five years. The imaging examinations were made regularly, with US every three months for the first year, every six months for the second and third years, and every year for the fourth and fifth years. A CT or MRI was done during the first, third, and fifth years. After five years, we were able to decide whether there had been sufficient evaluation with ultrasonography every 24 months.

The postoperative complications recorded were: facial nerve weakness, transient facial nerve injury, or facial paralysis; dysaesthesia of the great auricular nerve; salivary fistula; Frey syndrome; capsular rupture; and recurrence. Weakness of the facial nerve and dysaesthesia of the great auricular nerve were further characterised using a threshold of more than six months of symptoms being present to distinguish persistent from transient conditions.

Statistical analysis

The significance of the difference between recurrence rates and complications of the two techniques was calculated using a univariate analysis of each variable with Fisher’s exact test. The level of significance was set at p ≤ 0.05.

The institutional review board approved the study and we have followed the guidelines of the Helsinki Declaration.

Results

A total of 261 patients with pleomorphic adenomas of the parotid were included: 125 male (48%) and 136 female (52%), mean (range) age 47 (14-78) years. The mean (SD) duration of follow up was 65 (3) months.

Of the 261 patients 210 were treated by extracapsular dissection and 51 by superficial parotidectomy ( Table 1 ). All patients had uneventful postoperative courses with no locoregional complications (incisional oedema or bleeding) or systemic complications ( Table 2 ). The mean (SD) hospital stay was 3 (1) days and 5 (2) days in the two groups, respectively (p=0.061). Histological examination of the surgical specimen by FNAB confirmed the diagnosis of pleomorphic adenoma in all patients.

Aug 5, 2020 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Surgical approach to parotid pleomorphic adenoma: a 15-year retrospective cohort study
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