Extracapsular dissection versus superficial parotidectomy in benign parotid gland tumors: The Vienna Medical School experience

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1 ORIGINAL ARTICLE Extracapsular dissection versus superficial parotidectomy in benign parotid gland tumors: The Vienna Medical School experience Lorenz Kadletz, MD, 1 Stefan Grasl, MD, 1 Matth aus C. Grasl, MD, 1 Christos Perisanidis, MD, 2 Boban M. Erovic, MD, PhD, MBA 1 * 1 Department of Otorhinolaryngology and Head and Neck Surgery, Medical University of Vienna, Vienna, Austria, 2 Department of Maxillofacial Surgery, Medical University of Vienna, Vienna, Austria. Accepted 12 August 2016 Published online 5 October 2016 in Wiley Online Library (wileyonlinelibrary.com). DOI /hed ABSTRACT: Background. The purpose of this study was to evaluate the clinical outcome in patients with benign parotid gland tumors after extracapsular dissection or superficial parotidectomy (SP). Methods. Eight hundred ninety-four patients with primary pleomorphic adenoma or Warthin s tumor were included from this study. Type and length of surgery, tumor size, resection margins, and complication rates were assessed. Results. Three hundred ninety-five (44.2%) extracapsular dissections and 499 SPs (55.8%) were performed. The rate of positive margins was significantly higher in the extracapsular dissection compared to the SP group (29.4% vs 10.2%; p <.0001). Recurrent disease (extracapsular dissection 5 7.2% vs SP 5 2.2%; p ) and permanent facial palsy were significantly more frequent after extracapsular dissection than SP (2.2% vs 0.6%; p ). Significant prolonged surgery time was observed after SP (146 vs 94 minutes; p <.0001). Conclusion. Because extracapsular dissection led to a significantly higher percentage of permanent facial palsy, recurrent disease, and positive resection margins compared to SP, we recommend SP for treating benign parotid gland tumors. VC 2016 Wiley Periodicals, Inc. Head Neck 39: , 2017 KEY WORDS: pleomorphic adenoma, Warthin s tumor, extracapsular dissection, superficial parotidectomy, postoperative complications, facial palsy, recurrent disease INTRODUCTION Salivary gland tumors represent a subgroup within the neoplasm of the head and neck and are subdivided into major and minor salivary gland tumors. Approximately 80% originate in the parotid gland and pleomorphic adenomas comprise between 50% and 70% of all benign parotid gland tumors. 1 Of all benign parotid tumors, 25% are diagnosed as Warthin s tumors. 2 The superficial parotid lobe lateral to the facial nerve is by far the most frequent localization of these benign lesions. 3,4 Because pleomorphic adenoma and Warthin s tumor have a tendency for local recurrence, clear resection margins are key to prevent recurrent disease. 5,6 A paradigm shift in the surgical treatment of benign masses of the parotid gland has occurred over the last decades mainly because of the risk of facial palsy and recurrent disease because of surgical treatment. In the beginning of parotid gland surgery, intracapsular dissection of pleomorphic adenomas and Warthin s tumors was the leading treatment strategy; however, this *Corresponding author: B. M. Erovic, MD, PhD, MBA, Department of Otorhinolaryngology and Head and Neck Surgery, Medical University of Vienna, W ahringer G urtel 18-20, A-1090 Vienna, Austria. boban.erovic@meduniwien.ac.at This work was presented at the 59th Annual Meeting of the Austrian Society of Oto-Rhino-Laryngology Head and Neck Surgery, Innsbruck, Austria, September 16 19, technique soon became obsolete as a result of its high recurrence rates. 7,8 Today, the best therapeutic management of pleomorphic adenomas and Warthin s tumors is one of the most controversially discussed topics in head and neck surgery. 3,9 Superficial parotidectomy (SP) with full dissection of the facial nerve is a widely accepted method. This technique is routinely performed for benign parotid tumors at most centers worldwide. Exploration and dissection of the facial nerve in an anterograde or retrograde manner provides excellent control of the nerve s integrity. 10 In contrast, extracapsular dissection is defined by a careful dissection of the tumor and its capsule without identifying and dissecting the facial nerve. Proponents of this concept propagate extracapsular dissection as the method of choice for selected benign parotid gland tumors because of a decreased risk and rate of (1) permanent or temporary facial palsy, (2) shorter time of surgery, and (3) less postoperative scarring because of nonexposure of the facial nerve compared to the SP technique. 3,10,11 However, the authors also conclude that the extracapsular dissection technique seems to be more suited for experienced surgeons and smaller sized tumors. 3,12 16 In this context, we wanted to evaluate the clinical outcome of all patients with a pleomorphic adenoma or a Warthin s tumor of the parotid gland who were consecutively introduced to surgery in the last 55 years at the Medical University of Vienna. The purpose of this study 356 HEAD & NECK DOI /HED FEBRUARY 2017

2 OUTCOMES OF PAROTID GLAND SURGERY was to investigate possible differences in operative and postoperative outcomes between the extracapsular dissection and the SP technique. MATERIALS AND METHODS Patients This retrospective analysis was conducted at the Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna. Data of patients who underwent either extracapsular dissection or SP between the years 1960 and 2015 were investigated. All patients with a histologically confirmed pleomorphic adenoma or Warthin s tumor of the parotid gland were included in this study. Patients with insufficient medical reports were excluded from analysis. In addition, patients who underwent surgery because of recurrent disease were also excluded from the study. This study was approved by the institutional research board (1795/2015). Clinical data Sociodemographic characteristics for each patient were obtained from the hospital medical records. Reports were explored with regard to the surgical method (SP with dissection of the facial nerve vs extracapsular dissection), length of surgery, and surgeon. Moreover, data of resection margin and tumor size were obtained from histopathologic findings. The largest transversal diameter according to the histopathologic report was taken into consideration. Resection margin status was classified as free when a clear resection margin was reported or as positive in case of tumor within 1 mm of the resection margin or the capsule was ruptured. Postoperative complications were assessed as followed: permanent and temporary facial palsy, recurrence rate, Frey s syndrome, seroma formation, postoperative bleeding, and salivary fistula formation. In particular, permanent facial palsy was defined as a facial palsy lasting longer than 1 year. Statistics Sociodemographic data and postoperative outcome, including complications, were analyzed using descriptive statistics. Fisher s exact test was used to analyze the categorical data of postoperative complications for statistical significance. Moreover, independent t test was performed to evaluate tumor size and time of surgery. SPSS software version 21.0 (SPSS, Chicago, IL) and Prism GraphPad software (GraphPad Software, La Jolla, CA) were used to analyze data. RESULTS Patient data Eight hundred ninety-four patients were diagnosed with either a pleomorphic adenoma (n 5 514; 57.5%) or Warthin s tumor (n 5 380; 42.5%) of the parotid gland. All patients underwent parotid gland surgery at the General Hospital of Vienna between the years 1960 and At the time of surgery, mean age for all patients was 55.5 years (range, years). Of the entire cohort, TABLE 1. Demographic and clinical data of 894 patients with pleomorphic adenoma or Warthin s tumor of the parotid gland. Variables No. of patients (%) Sex Female 455 (50.9) Male 439 (49.1) Age, y Mean 55.5 Median 53 Range Diagnosis Pleomorphic adenoma 514 (57.5) Warthin s tumor 380 (42.5) Side Left 472 (52.8) Right 422 (47.2) FNAC, preoperatively Yes 103 (11.5) No 791 (88.5) Abbreviation: FNAC, fine-needle aspiration cytology. 50.9% were women (n 5 455) and 49.1% were men (n 5 439; Table 1). Clinical data The majority of patients was treated with SP (n 5 499; 55.8%), whereas, in 44.2% of them, extracapsular dissection (n 5 395) was performed. Over the study period of 55 years, 55 different surgeons conducted the operations. The number of performed SP and extracapsular dissection cases over time is shown in Figure 1. Looking in particular at the surgical technique, we observed that, before the 1990s, experienced surgeons mainly performed extracapsular dissections, whereas between 1990 and 2015 surgeons at all educational levels mainly performed SPs. The mean duration of surgery for patients who underwent extracapsular dissection and SP was 94 minutes (range, minutes) and 146 minutes (range, minutes), respectively. The length of time of the surgery for SP was 1.55 times longer than for extracapsular dissection (p <.0001). Even when we take into consideration that surgical loupes were introduced after 2007, no relevant abbreviation in duration of SP (mean of 142 minutes after 2007 vs mean of 146 minutes before 2007) could be observed. After SP, 89.8% (n 5 448) of all patients showed free resection margins compared to 70.6% (n 5 279) after extracapsular dissection (p <.0001). The size of the tumors was also compared between the SP and extracapsular dissection groups. Interestingly, the mean transversal diameter of tumors treated by SP and extracapsular dissection was 23.6 mm (range, 5 60 mm) and 13.9 mm (range, 4 45 mm), respectively, showing that tumors in the SP group were 1.7 larger than tumors in the extracapsular dissection group (p <.0001). Complications after surgery The tumor recurrence rate was significantly different between the SP and extracapsular dissection groups. In particular, 2.2% (n 5 11) and 7.3% (n 5 29) developed HEAD & NECK DOI /HED FEBRUARY

3 KADLETZ ET AL. FIGURE 1. Number of cases treated with either superficial parotidectomy or extracapsular dissection over time. recurrent disease after SP and extracapsular dissection, respectively (p ; Figure 2). In particular, 50% of all the patients in our study who developed recurrent disease had no clear resection margins after the first surgery. Temporal facial palsy developed in 10.6% of the patients (n 5 53) after SP and lasted 35.1 days (range, days). Forty-five patients (11.4%) showed a temporary dysfunction of the facial nerve after extracapsular dissection and palsy lasted for 36.7 days (range, 7 60 days; p ). Most importantly, the permanent facial palsy rate was significantly higher in the extracapsular dissection group compared to the SP group (p ). Three patients (0.6%) after SP and 9 patients (2.2%) after extracapsular dissection had a facial palsy after 1-year follow-up. Moreover, we evaluated the effect of using surgical loupes for SP. Interestingly the introduction of surgical loupes had no influence on the incidence of transient and permanent facial palsy (from 11.9% to 9.0%; p ; from 0.72% to 0.47%; p , respectively) in our study group. Frey s syndrome occurred in 1.4% (n 5 7) and 2.0% (n 5 8) of all patients after SP and extracapsular dissection (p ), respectively. Forty-two patients (8.4%) after SP and 40 patients (10.1%) after extracapsular dissection (p ) developed a seroma, and postoperative bleeding occurred in 5 (1%) and 2 (0.5%) patients after SP and extracapsular dissection (p ), respectively. Salivary fistula occurred in 9 patients (1.8%) after SP and in 6 patients (1.5%) after extracapsular dissection (p ; Table 2). DISCUSSION Historically, after World War II and, in particular, in the period between the early 1960s and 1980s, extracapsular dissection was the standard treatment of benign parotid gland tumors at the Department of Otorhinolaryngology in Vienna, Austria. Three decades later, most of the surgeons realized that extracapsular dissection was a timesaving procedure; however, the rate of recurrent disease and facial palsy was unproportionally high. From the early 1990s on, the policy of surgical treatment at our department changed and SP, defined by wide tumor resection with facial nerve dissection, became the treatment of choice for benign tumors of the parotid gland. Nevertheless, surgeons still have frequently discussed limited resections for benign parotid tumors but, since Mantsopoulos et al 3 published their largest series on extracapsular dissection, a very controversial discussion was initiated. In particular, Mantsopoulos et al 3 propagated and still propagate the minimal invasive concept of extracapsular dissection because of the significant less time of the surgery and frequent complications compared to SP. Because our department had a considerable large number of patients treated between the 1960s and 1990s, it was obvious to compare the clinical outcome and time of surgery between these 2 surgical techniques. To the best FIGURE 2. Postoperative complications after extracapsular dissection and superficial parotidectomy (*statistical significance). 358 HEAD & NECK DOI /HED FEBRUARY 2017

4 OUTCOMES OF PAROTID GLAND SURGERY TABLE 2. Summarized data of 894 patients who underwent superficial parotidectomy or extracapsular dissection. Variables SP (%) Extracapsular dissection (%) p value No. of patients 499 (55.8) 395 (44.2) Length of surgery, min <.0001 Mean SD SEM Lower 95% CI of mean Upper 95% CI of mean Size, mm <.0001 Mean SD SEM Lower 95% CI of mean Upper 95% CI of mean Free resection margin 448 (89.8) 279 (70.6) <.0001 Recurrence 11 (2.2) 29 (7.2).0003 Temporary facial palsy 53 (10.6) 45 (11.4).7469 Permanent facial palsy 3 (0.6) 9 (2.2).0396 Frey s syndrome 7 (1.4) 8 (2.0).1185 Seroma formation 42 (8.4) 40 (10.1).4147 Bleeding 5 (1.0) 2 (0.5).4734 Salivary fistula 9 (1.6) 6 (1.5).7991 Abbreviations: SP, superficial parotidectomy; CI, confidence interval. of our knowledge, this study includes the largest collective of performed SPs and the second largest collective of conducted SPs and extracapsular dissections in total (Table 3). 3,16 28 One of the most devastating complications in parotid surgery is recurrent disease. Especially pleomorphic adenomas that harbor a significant risk for recurrent disease 16 with a slightly higher recurrence rates after extracapsular dissection (0% to 10%) compared with SP (0% to 6.7%; Table 3). 3,16 28 In accordance with the literature, we found a significantly higher rate of recurrent disease after extracapsular dissection compared with SP. In particular, recurrence happened in 7.2% of the patients after extracapsular dissection and only 2.2% of the patients after SP. It is well established that recurrent disease of parotid gland tumors is directly linked to positive resection margins, thus one of the most critical issues in parotid surgery is the achievement of clear margins. Witt et al 29 observed that focal capsular exposure occurs during surgical resection of pleomorphic adenoma and highlighted that minimal margin surgery in extracapsular dissection results in a higher rate of capsular exposure. In our study, we show that the rate of complete resection with clear margins was significantly higher in the SP group compared to the extracapsular dissection group. Tumor size is another factor that has an impact on the achievement of clear resection margins. In our study, we demonstrate that the mean size of the resected masses TABLE 3. Studies investigating the differences of superficial parotidectomy and extracapsular dissection. SP Extracapsular dissection Author No. of patients PFND, % TFND, % RD, % No. of patients PFND, % TFND, % RD, % Gleave * * * 257 * * 1.5 Martis * * * 78 * * * Prichard Natvig * * * * 0 Hancock Marti Witt McGurk Ghosh * * * 22 * * * Uyar Barzan * * 10 Orabona Iro * * * * 0 Mantsopoulos * * * * Abbreviations: SP, superficial parotidectomy; PFND, permanent facial nerve dysfunction; TFND, temporary facial nerve dysfunction; RD, recurrent disease. * Results not clearly presented. HEAD & NECK DOI /HED FEBRUARY

5 KADLETZ ET AL. was 1.7 times larger in patients treated with SP compared with patients treated with extracapsular dissection. Our results are in line with current literature recommending extracapsular dissection mainly for smaller sized tumors, whereas SP is considered a surgical method for all tumor sizes. 3,16,23,27 Another challenging factor in parotid surgery is the function of the facial nerve. The rate of permanent facial palsy varies between 0% and 13.3% after extracapsular dissection and 0% and 8.9% after SP (Table 3). 3,16 28 In their large cohort study, Mantsopoulos et al 3 showed that 1.9% of patients developed permanent facial palsy after extracapsular dissection and 9.8% of patients after nonextracapsular dissection cases. In our study, 0.6% of patients developed permanent facial palsy after SP and 2.2% of patients after extracapsular dissection. Thus, permanent dysfunction of the facial nerve was 3.6 times more common after extracapsular dissection; therefore, the difference was significant. Looking at the incidence of temporary facial palsy, recently published studies reported rates ranging between 8.2% and 32.3% after SP and 0% and 9.7% after extracapsular dissection. Our results are in accordance with the current literature showing 10.6% and 11.4% after SP and extracapsular dissection, respectively. 3,16 28 Additionally, we investigated the effect of surgical loupes during SP. Despite the fact that surgical telescopes showed no benefit regarding the length of surgery, they led to a reduction of postoperative facial palsy. After the establishment of magnifying lenses in 2007, complication rates of transient and permanent facial palsy decreased significantly after SP. Over the last years, human and medical resources are gaining more and more value and the length of the surgery has become a huge issue in healthcare management. More than half of the study patients were treated with SP that lasted 1.55 times longer than extracapsular dissection. CONCLUSION The optimal surgical approach for benign parotid gland tumors remains a highly controversial issue. In this study, we evaluated the outcome of patients with benign parotid gland tumors who underwent either SP or extracapsular dissection. In our cohort, we showed that SP results in superior clinical outcome with regard to permanent facial palsy, rate of clear margins, and recurrent disease when compared to extracapsular dissection. Moreover, SP may be applied for all benign tumors regardless of their size and localization. Although more time-consuming than extracapsular dissection, SP will remain the treatment of choice for benign parotid lesions at our institution. REFERENCES 1. Tweedie DJ, Jacob A. 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