What Happens Next: Unexpected Malignancies After Extracapsular Dissection of Parotid Tumors

Abstract This retrospective cohort study aimed to evaluate the oncologic safety and functional outcomes of extracapsular dissection (ECD) as the primary surgical approach in patients with low-grade malignant parotid tumors. Conducted at a tertiary academic center, the study included 17 patients treated with ECD between 2012 and 2020, all of whom had preoperative benign or non-diagnostic cytology and were followed for at least 60 months. The primary outcome measures included recurrence rate, need for additional surgery or adjuvant therapy, facial nerve preservation, and disease-free survival. With a mean follow-up of 89.7 months, no local or regional recurrence was observed. ECD alone was sufficient in 76.5% of cases; three patients underwent completion superficial parotidectomy due to positive margins, yet no residual tumor was identified. Only two patients (11.8%) required adjuvant therapy due to perineural invasion. All patients maintained normal facial nerve function, and two died from unrelated causes while the remainder remained disease-free. These findings suggest that in carefully selected patients with small, well-circumscribed, low-grade parotid malignancies, ECD may provide oncologic outcomes comparable to more extensive surgery while minimizing surgical morbidity. ECD thus represents a viable definitive treatment option aligned with evolving, risk-adapted approaches to salivary gland cancer management. Keywords:Parotid gland tumor, extracapsular dissection, low-grade malignancy, conservative surgery, facial nerve preservation, salivary gland cancer, oncologic outcomes, functional results not-yet-known not-yet-known not-yet-known unknown Key Points 1. Extracapsular dissection (ECD) is increasingly utilized as a less invasive technique for parotid tumors initially presumed to be benign. 2. Unexpected malignancies following ECD represent a clinical dilemma regarding the adequacy of initial surgery. 3. Our long-term single-institution experience demonstrates that oncologic outcomes can remain favorable in carefully selected low-grade malignancies. 4. In most cases, no additional surgery or adjuvant therapy was required, with no recurrence observed during follow-up. 5. These findings support a tailored, risk-adapted surgical strategy for selected parotid tumors discovered to be malignant postoperatively.

Malignant tumors of the parotid gland constitute a heterogeneous group with diverse biological behaviors, histological subtypes, and metastatic potential. The traditional surgical standard has been total or superficial parotidectomy, often with elective neck dissection, to ensure oncologic control [1,2]. However, recent evidence suggests that a histology- and grade-based tailored approach may be appropriate for selected low-grade malignancies, potentially reducing morbidity without compromising safety [2,3]. Extracapsular dissection (ECD), long used for benign tumors due to its advantages in facial nerve preservation and reduced complications, is now being explored in low-grade malignant cases. Studies have shown ECD can yield oncologic outcomes comparable to more extensive surgery in small, well-circumscribed, low-grade tumors lacking adverse features [1,4]. ASCO and ESMO guidelines support limited resection strategies for certain T1-T2, low-grade tumors. Still, concerns remain regarding residual disease, recurrence, and the need for adjuvant therapy. This study aimed to assess the oncologic and functional outcomes of ECD in low-grade malignant parotid tumors, hypothesizing that it offers comparable oncologic safety with improved functional preservation in well-selected patients.

This retrospective cohort study was conducted at the Department of Otorhinolaryngology, Ege University Faculty of Medicine between January 2012 and 2025. The aim was to evaluate oncologic and functional outcomes of extracapsular dissection (ECD) in parotid gland tumors. The study received institutional ethical approval (Approval No: E-92659746-020-2332124), and all patients provided written informed consent. The study followed the Declaration of Helsinki and STROBE guidelines. Eligible patients had undergone ECD between 2012 and 2020, had preoperative FNAB results reported as benign or non-diagnostic, and were diagnosed postoperatively with low-grade malignancy. A minimum of 60 months of follow-up was required. Patients with non-primary tumors, suspected high-grade malignancy, recurrences, or preoperative facial nerve dysfunction were excluded. Seventeen patients (6 males, 11 females) were included. All surgeries were performed by a single head and neck surgeon (K.O.). Preoperative workup included clinical exam, contrast-enhanced MRI, FNAB, and facial nerve assessment. Adjuvant therapy decisions were made by a multidisciplinary tumor board. Primary outcomes included recurrence, need for further surgery or adjuvant therapy, disease-free survival, and facial nerve function. Data were collected retrospectively, and all patients were contacted for final follow-up.

Seventeen patients met the inclusion criteria. Ages ranged from 18 to 86 years (mean: 53.3, SD: 18.4), and 64.7% were female. Demographic and clinicopathological features are summarized in Table 1. Preoperative FNAB revealed benign findings in 64.7% and non-diagnostic results in 29.4% of cases. Postoperative histology identified low-grade mucoepidermoid carcinoma in 52.9%, adenoid cystic and acinic cell carcinoma each in 17.7%, and one case each of intermediate-grade mucoepidermoid and secretory carcinoma (5.9%). ECD alone was sufficient in 76.5% of patients. Three required secondary superficial parotidectomy due to positive margins, though no residual tumor was found. Adjuvant therapy was administered to two patients (11.8%) due to perineural invasion; the remainder did not require further treatment. The mean follow-up was 89.7 months (range: 61–138). No recurrences were observed. Two patients died of unrelated causes; all others remained disease-free. Table 1. Clinicopathological features and outcomes of 17 patients undergoing ECD for low-grade parotid malignancy.

This study supports extracapsular dissection (ECD) as a safe and effective surgical approach in selected patients with low-grade malignant parotid tumors. With a mean follow-up nearing 90 months, no recurrences were observed, and all patients preserved normal facial nerve function, underscoring both oncologic and functional success. ECD appears to offer disease control comparable to more extensive procedures while reducing morbidity. Our findings are consistent with prior literature advocating tailored management in salivary gland malignancies. Although retrospective design and small sample size are limitations, the homogeneous cohort and long follow-up enhance validity. Accurate preoperative tumor grading remains a challenge, especially with benign or non-diagnostic FNAB results.These outcomes reinforce the clinical applicability of ECD in personalized treatment strategies at experienced centers. While broader adoption requires multicenter trials, current evidence supports its use in selected cases. Historically, malignant parotid tumors have been managed with total or superficial parotidectomy, often combined with neck dissection to ensure oncologic control [1,2]. However, salivary gland malignancies are biologically diverse, with over 20 histological subtypes showing varying aggressiveness and metastatic potential. While some subtypes demand radical surgery, others, such as acinic cell carcinoma or low-grade mucoepidermoid carcinoma, are indolent and well-circumscribed [1–3]. ASCO guidelines recommend tailoring surgical extent to tumor histology, particularly endorsing conservative resections for early-stage, low-grade tumors. Surgery with negative margins remains key. Clinical series report excellent local control with surgery alone for T1–T2 low- to intermediate-grade tumors, even with narrow margins when adverse features are absent [4]. Given this variability, a uniform surgical approach may not suit all cases. Instead, risk-adapted strategies can reduce morbidity while maintaining oncologic safety [5,6]. Our findings align with this view, suggesting that patients with small (<4 cm), low-grade tumors may achieve excellent disease control through conservative surgery. Prior studies have assessed the feasibility of ECD in such contexts [1,7].Mantsopoulos et al. (2015) described patients presumed to have benign tumors who were later found malignant post-ECD. Among 25 cases undergoing completion parotidectomy, only three had residual tumor, indicating that initial conservative surgery did not compromise safety [7]. They also highlighted functional advantages of avoiding extensive surgery, as most patients retained normal function [7,8].In 2023, Mantsopoulos et al. reported the longest follow-up of patients treated with ECD alone. Though our study’s follow-up exceeds theirs, their 16 cases with low-grade tumors treated solely with ECD showed 100% local control and disease-specific survival at five years [9].Our results echo those findings. Similar to Mantsopoulos et al., we observed effective oncologic control in well-circumscribed, low-grade tumors. Lim et al. documented a 90% local control rate using conservative parotid surgery in selected cases [4]. A systematic review by Quer et al. found that 88–91% of patients remained disease-free after limited resection with negative margins [8,9]. These outcomes suggest that, in select cases, ECD may offer results comparable to traditional parotidectomy while reducing facial nerve dysfunction [8,9].Our highly selected cohort—characterized by low-grade histology, T1 stage, superficial tumors, no nodal involvement, and negative margins—demonstrated outcomes equivalent to standard parotidectomy, supporting a personalized surgical approach [8–10].Nonetheless, conservative surgery is not universally effective. Higher recurrence rates are reported with overly minimal techniques like enucleation [10]. This underscores the need for appropriate patient selection and meticulous technique. ECD or partial parotidectomy should only be used when negative margins are achievable [2,3].Our strategy reserves conservative surgery for cases with favorable preoperative characteristics and mandates confirmed negative margins. When margins are uncertain or adverse features exist, we recommend completion surgery or adjuvant therapy as per guidelines.An important question remains: is definitive surgery necessary for all parotid malignancies, or could limited excision followed by observation suffice in select low-risk cases? Our findings and current literature suggest observation may be a viable option in such scenarios, a view increasingly shared by head and neck oncology experts [9,10].

Our findings suggest that a one-size-fits-all surgical approach may not be ideal for malignant parotid tumors. Instead, tailoring surgery based on tumor histology, grade, and clinical features can maintain oncologic efficacy while minimizing morbidity. While total parotidectomy remains the standard, growing evidence supports more selective options in low-risk patients. Specifically, ECD appears to be an oncologically safe and functionally favorable alternative for selected low-grade tumors, reducing surgical morbidity without compromising outcomes. To validate ECD as a standard of care, larger prospective, multicenter studies are needed. In well-selected cases, ECD offers excellent disease-free survival and minimal recurrence, provided that meticulous patient selection and long-term follow-up are ensured. 1. Mantsopoulos K, Koch M, Iro H. (2017). Extracapsular dissection as sole therapy for small low-grade malignant tumors of the parotid gland. The Laryngoscope, 127: 1804–1807. https://doi.org/10.1002/lary.26482 2. van Herpen C, Vander Poorten V, Skalova A, et al. (2022). Salivary gland cancer: ESMO-European Reference Network on Rare Adult Solid Cancers (EURACAN) Clinical Practice Guideline. ESMO Open, 7(6):100602. https://doi.org/10.1016/j.esmoop.2022.100602 3. Geiger JL, Ismaila N, Beadle B, et al. (2021). Management of Salivary Gland Malignancy: ASCO Guideline. J Clin Oncol, 39(17):1909–1941. https://doi.org/10.1200/JCO.21.00449 4. Lim YC, Lee SY, Kim K, et al. (2005). Conservative parotidectomy for the treatment of parotid cancers. Oral Oncol, 41(10):1021–1027. https://doi.org/10.1016/j.oraloncology.2005.06.004 5. Di Villeneuve L, Souza IL, Tolentino FDS, et al. (2020). Salivary Gland Carcinoma: Novel Targets to Overcome Treatment Resistance in Advanced Disease. Front Oncol, 10:580141. https://doi.org/10.3389/fonc.2020.580141 6. Bou Zerdan M, Kumar PA, Zaccarini D, et al. (2023). Molecular Targets in Salivary Gland Cancers: A Genomic Analysis of 118 Mucoepidermoid Carcinomas. Biomedicines, 11(2):519. https://doi.org/10.3390/biomedicines11020519 7. Mantsopoulos K, Velegrakis S, Iro H. (2015). Unexpected Detection of Parotid Gland Malignancy during Primary ECD. Otolaryngol Head Neck Surg, 152(6):1042–1047. https://doi.org/10.1177/0194599815578104 8. Mantsopoulos K, Mueller S, Goncalves M, et al. (2019). Completion surgery after ECD of low-grade parotid tumors. Head Neck, 41(9):3383–3388. https://doi.org/10.1002/hed.25863 9. Mantsopoulos K, Thimsen V, Sievert M, et al. (2023). Limited parotid surgery as sole treatment: Long-term results. Am J Otolaryngol, 44(2):103735. https://doi.org/10.1016/j.amjoto.2022.103735 10. Quer M, Olsen KD, Silver CE, et al. (2020). Is There A Role for Limited Parotid Resections? Surgeries, 1(1):2–9. https://doi.org/10.3390/surgeries1010002 Information & Authors Information Version history Copyright This work is licensed under a Non Exclusive No Reuse License. Authors Metrics & Citations Metrics Article Usage 154views 84downloads Citations Download citation Kerem Ozturk, Efe İşler. What Happens Next: Unexpected Malignancies After Extracapsular Dissection of Parotid Tumors. Authorea. 05 June 2025. DOI: https://doi.org/10.22541/au.174910876.60327627/v1 DOI: https://doi.org/10.22541/au.174910876.60327627/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu.