Paediatric saliva gland surgery: a 10-year review of indications, complications and outcomes

Introduction

Salivary gland disease is a rare entity in the paediatric population. Despite several extensive retrospective reviews in the overall management of salivary gland disease (both medical and surgical) (1-3), small patient cohorts do not offer clear advice on the gold standard of therapies in these children. Even when looking at surgical management alone, very few authors have attempted to present an institutional perspective of their operative approach to all salivary gland disease, rather choosing to focus on one subset of the population, particularly in the oncological (4-6) and drooling (7) patients.

This paper reviews the surgical management of all major salivary gland disease in a large tertiary paediatric referral centre over 10 years. The primary aim of this study is to retrospectively analyse the outcomes, complications, and clinical improvements in paediatric patients who underwent salivary gland surgery over a 10-year period. Secondary aims include:

• Comparison of the efficacy and postoperative outcomes of transcervical and transoral surgical approaches for sialorrhoea (drooling) focusing on the differences in length of hospital stay, feeding outcomes, complications and overall recovery and clinical improvement based on the type of surgery undertaken.
• Examine the demographic and clinical characteristics of patients undergoing surgery for oncologic/neoplastic, obstructive/inflammatory, and infective conditions, with a particular focus on surgical modalities and their outcomes.
• Identify trends in complications, with the goal of optimising surgical approaches and improving patient recovery and quality of life.

Methods

This retrospective study was undertaken at the Royal Children’s Hospital, Melbourne, Australia. The study is reported according to the STROBE reporting guidelines (available at https://www.theajo.com/article/view/10.21037/ajo-24-39/rc). The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Ethics approval was sought and approved by the Human Research and Ethics Committee at The Royal Children’s Hospital Melbourne (QA/93034/RCHM-2023). Because of the retrospective nature of the research, the requirement for informed consent was waived. All cases of primary head and neck salivary gland surgery were retrospectively identified between January 2011 and December 2022. Medical records were reviewed for demographic and clinical data including age, gender, American Society of Anaesthesiologists (ASA) score, indication and type of surgery, histopathology (where applicable), length of stay in hospital, complications and duration of follow up. Data was further extracted from follow up visits including resolution of symptoms, complications and overall outcome of surgery where possible. Outcome measurements for the drooling cohort were used based off clinical follow up outpatient notes and whether patients were noted to subjectively have reported poorer oral intake during their inpatient stay and clinical improvement at the end of their follow up period.

Statistical analysis

All statistical analysis was undertaken on IBM SPSS Statistics (Armonk, New York, USA). Distribution of data was analysed using the Shapiro-Wilk test. Non parametric testing using the Mann-Whitney test was undertaken to determine the effect of different surgical modalities on median length of stay, complications and outcomes in the drooling population. Univariate tests were applied to demographic variables including age, gender and ASA score of patients. Significance was considered when P<0.05.

Results

Overall, there were 109 procedures performed on major salivary gland pathology throughout the study period in 101 patients. Nine cases were excluded due to insufficient data for analysis. One case was included for qualitative analysis only due to its complexity and clearly being an outlier for patient outcomes (see oncological/neoplastic cohort). The mean age was 11.1±5.2 years with a slight female predisposition (n=51; 52%). The average length of stay in hospital was just under 2 days (1.9±1.3) with a mean ASA score over 2 (2.4±0.9) alluding to the complexity of the cohort. Further breakdown of demographics per subcategory are referred to in Table 1.

Drooling

There were 60 cases of primary salivary gland surgery for sialorrhoea. This included 23 transcervical bilateral submandibular gland excisions with or without concurrent unilateral parotid duct ligation, and 37 transoral bilateral sublingual gland excision with rerouting of submandibular ducts (see Table 2). Eight patients were excluded due to incomplete follow up data. Three patients had revision surgery due to ongoing sialorrhoea, all of which had primary transoral surgery. Patients who underwent transcervical surgery were significantly younger than their transoral counterparts (P=0.003). There was a trend towards the transcervical group being more comorbid (ASA score 3.1±0.55 to 2.8±0.51; P=0.056) and having a shorter length of stay (1.9±1.4 to 2.3±1.0 days; P=0.206) although neither of these reached statistical significance. Transoral surgery was associated with poorer feeding during their inpatient stay [22 (68%)] compared to transcervical surgery [2 (9%)] (P<0.001). Clinical improvement was similar between the two groups (P=0.646). There was no documented nerve palsy or surgical site infection in either group.

Oncologic/neoplastic

Overall, there were fourteen procedures performed for neoplastic or presumed oncological disease. There was a female predisposition (n=8; 62%) with a mean age of 10.5±4.8 years (see Table 1). One outlier was excluded from primary demographic analysis due to rarity of diagnosis (sialoblastoma) requiring excessive length of stay for reconstructive and chemotherapeutic requirements. This patient required a total parotidectomy with temporomandibular joint disruption, zygomectomy and infratemporal fossa clearance including resection of pterygoid plates to achieve clear margins at the skull base. The most common surgery performed in the neoplastic group was parotidectomy including 10 primary parotidectomy surgeries, 1 revision parotidectomy (referred from an external source) and 1 revision major oncologic clearance surgery (remnant skull base/parapharyngeal disease from a primary resection) noted previously (see Table 3). The most common benign pathology encountered was pleomorphic adenoma (38%) and the most common malignant pathology was sialoblastoma (15%). The age range of pleomorphic adenoma was between 11–16 years, with additional cases including a 9-year-old with mucoepidermoid carcinoma, a 14-year-old with acinic cell carcinoma, and two cases of sialoblastoma in a 2-year-old and a 5-day-old. There were 2 submandibular gland surgeries performed with no documented complications for neoplastic pathology.

Obstructive and inflammatory

Fifteen procedures were performed for obstructive/inflammatory disease (see Table 4). This included 7 sublingual gland excisions for ranula, 6 submandibular gland excisions (4 primary and 2 secondary procedures) for sialadenitis, 2 transoral removal of calculi and 1 parotidectomy for sialectasis. The most common obstructive pathology was ranula whilst the most common inflammatory condition was sialadenitis. There were two documented cases of transient marginal mandibular nerve weakness following submandibular gland removal for sialadenitis and one case of wound dehiscence following sublingual gland removal for a ranula which resolved spontaneously.

Infective

Five primary and one revision parotidectomy were performed for mycobacterium avium complex (MAC) infection (see Table 5). The mean age of 2.5 years made this the youngest subcategory of the cohort (see Table 1). There were two documented cases of keloid/hypertrophic scar formation (likely reflecting the chronic infective process), one case of Frey’s syndrome (gustatory sweating) and as previously noted, one case requiring further surgery in the setting of residual infective disease.

Other

There were five further cases that included two submandibular gland dermoid cysts, a parotid arteriovenous malformation, a type 1 branchial arch anomaly and a sublingual lymphovascular malformation. Their demographics are summarised in Table 1. There were two surgical site infections that responded to medical management and one facial nerve neuropraxia that resolved after four months.

Discussion

This retrospective cohort study adds to the somewhat scarce literature pertaining to surgical treatment of paediatric salivary gland disease. To the authors best knowledge, this is a unique qualitative and quantitative review of surgical management that provides further insight into these rare but important pathologies.

Primary neoplasms of the salivary gland remain a rare entity, making up 5% of all reported salivary gland tumours (4) and less than 10% of all paediatric head and neck tumours (6). Malignancy rates for a paediatric salivary gland mass are quoted between 35–50% (5,8) and therefore a clinician must maintain a high level of clinical suspicion when presented with an isolated salivary gland mass in a child.

Salivary gland neoplasms most commonly affect the parotid gland and are more likely to harbour malignant pathology than submandibular tumours (9,10). Pleomorphic adenoma and mucoepidermoid carcinomas are the most common benign and malignant pathology (4). Surgical resection is still the primary treatment modality. Compared to the adult population, both major and minor salivary glands in children are more likely to harbour malignant tumours (5,8).

The study population largely reflected these findings with 82% of primary neoplasms being parotid in origin and 45% of all tumours being malignant. The most common pathology was pleomorphic adenomas (36%) followed by sialoblastoma (18%), mucoepidermoid, acinic cell carcinoma and rhabdomyosarcoma. The youngest child with mucoepidermoid carcinoma diagnosis was 9 years old. Other pathologies encountered when removing isolated lesions included branchial anomaly, foregut duplication cyst and dermoid cysts. Interestingly, the most common malignant pathology encountered was sialoblastoma . Sialoblastoma (or embryomas) are extremely rare tumours found only in newborns/neonates and said to originate from the ductal or secretory epithelium of the salivary gland. Sialoblastoma displays aggressive behaviour and surgical resection is the modality of choice (11). They are at high risk of locoregional recurrence if not completely excised although are unlikely to undergo distant metastasis (6,11).

The risk of facial nerve palsy remains high in the paediatric population, with rates quoted between 15–50% (4,12,13). Such a large variance may be due to the altered anatomy seen in the paediatric population (an underdeveloped mastoid with a superficial nerve) and higher rates of malignant pathology (8,13). Other common complications include hypertrophic scar formation and Frey’s syndrome. Of the 16 parotidectomy procedures performed, only one patient suffered a permanent facial nerve palsy from a deep lobe resection of an aggressive sialoblastoma. There was no documentation of gustatory sweating or keloid within this oncological population with the treatment largely well tolerated. There were no mortalities in the study population.

The surgical approach to the drooling child remains somewhat complicated. Surgical approaches include transoral [submandibular/parotid duct ligation (2 or 4) (14-18), submandibular duct rerouting with or without sublingual gland removal (19-24)], transcervical methods [submandibular gland removal (25)] or a combination of both (26). Management often involves a multi-disciplinary team of allied health professionals (nursing staff, speech therapists and physiotherapists), physicians (paediatricians, neurodevelopmental physicians, neurologists) and surgeons. The decision for surgery needs to take into account patient preferences, previous treatment, comorbidities and the type of drooling present (7).

Overall, the majority of patients in the study surgical cohort were neurodevelopmentally impaired (cerebral palsy, muscular dystrophy) with an elevated anaesthetic risk. All patients underwent multidisciplinary consideration through a subspecialised drooling clinic with two broad categories of surgical intervention performed: (I) transoral rerouting of submandibular ducts and sublingual gland excision or (II) transcervical submandibular gland excision with or without transoral parotid duct ligation.

Less invasive procedures such as duct ligation alone do exist but have variable outcomes and success rates, with patients often requiring further surgery (7). Despite the ease of the procedure, these children still are at risk of immediate issues such as perioral swelling, bleeding and pain (18) and on balance of risks versus benefits, 4-duct ligation has not been part of an algorithm for surgical treatment at the studies institution.

Salivary duct relocation is a more invasive but effective transoral procedure (13-18). This has been shown to be effective in reducing drooling although it is largely limited to children who are anterior droolers with reduced aspiration risk (7). Morbidity may also vary if sublingual gland removal is performed at the same time (to prevent ranula formation) in keeping with the study institution’s preference. Interestingly one paper showed no difference in drooling outcomes for submandibular duct rerouting with or without sublingual gland removal (20). Certainly, this retrospective study showed a trend towards increased lengths of stay were due to decreased oral intake, swelling and pain with the former being more prevalent in transoral compared to transcervical surgery. These provide important future considerations when offering this procedure to those who are already of higher perioperative risk due to their underlying syndromes or neurodisabilities.

Transcervical submandibular gland excision is another potential surgical intervention suitable for the management of both the anterior and posterior drooling child (25,26). Parotid duct ligation is also offered as part of this treatment to further reduce the major source of masticatory-induced salivary production (26). The main drawbacks of this technique include the morbidity entailed within transcervical approach to the neck and secondary parotid swelling. Interestingly, this study showed a trend to tolerating the procedure well, if not better than those undergoing transoral rerouting. There was a trend, albeit not statistically significant, to a shorter length of stay in hospital for those undergoing submandibular gland removal compared to transoral rerouting. Moreover, despite not traditionally being deemed first line surgical management in the drooling child, this same cohort was significantly younger than their transoral counterpart further alluding to how well the procedure was tolerated in what could be deemed a more at-risk surgical population with equivalent overall subjective improvement. These findings have been replicated in several previous studies. A case series of 93 children undergoing bilateral submandibular gland excision and parotid duct ligation showed subjective improvement in drooling of 87% (26). More recently an analysis of 45 neurologically impaired children whom had undergone submandibular gland excision showed improvement in robust objective outcomes measurements (25). Using a validated, semi-quantitative direct observational method, the authors showed drooling intensity was significantly reduced as a drooling quotient (in addition to overall subjective improvement) over 32 weeks. There was no documented lingual, hypoglossal or marginal mandibular nerve palsy highlighting the safety of this procedure and one that should be considered in the treatment of this pathology.

Obstructive salivary pathology is a rare paediatric entity. Patients underwent submandibular gland removal as either a primary (due to inflammation of the gland and/or obstruction) or secondary procedure following stone or ranula removal in six cases. Although patients tolerated the perioperative stay well, two cases of transient marginal mandibular nerve weakness prove this procedure is not without risk. Ranulas occur due to trauma or obstruction of the excretory ducts usually at the sublingual level. Although not uncommon, there are several options for management including marsupialisation with or without gland excision or sclerotherapy (27). All ranulas were managed via sublingual gland excision that was well tolerated with one patient suffering recurrence. For all these obstructive pathologies, less invasive techniques do exist albeit with an elevated risk of recurrence of symptoms. Thus, careful consultation is required when offering treatment to these patients (27,28).

Several patients in the cohort underwent superficial parotidectomy for the treatment of MAC infections . It is important to note that the only cases of Frey’s syndrome and keloid occurred in this group. At the study institution, there has been a trend moving away from aggressive surgical management in these patients, with the last superficial parotidectomy performed for MAC occurring over 6 years ago at the time of writing. With the aforementioned surgical risks (facial nerve injury, keloid, gustatory sweating) and the indolent nature of this disease one needs to consider a judicious and measured approach towards surgical management if salivary gland surgery is being considered (i.e., parotid or perifacial nodal involvement).

There are several limitations of this study. The study remains at risk of multiple forms of bias inherent in the retrospective nature of its design. Furthermore, data collection of patients relies heavily on the assumption of correct coding of procedures, documentation of postoperative findings (complications) and follow up (overall improvement) by the surgeon and/or surgical units. In addition, no validated outcome measures were used to objectively measure feeding outcomes and overall improvement in the drooling population, relying on the reporting of patients and documentation of practitioners. Despite these short comings, this paper provides unique and important holistic commentary on the surgical management of salivary gland disease in the paediatric population.

Conclusions

This retrospective cohort series adds to and validates previous findings regarding the operative management of salivary gland disease in the paediatric population. Although rare, malignancy rates of salivary gland disease remain higher compared to their adult counterparts. Furthermore, operative management remains challenging with patients more at risk of complications including facial nerve neuropraxia or palsy. The algorithm for management of the drooling child remains somewhat complex and requires a multidisciplinary and patient centred approach to management. Both transoral and transcervical management are efficacious in the treatment of sialorrhea and should both be considered in the primary operative management of these children. Inflammatory and obstructive pathology responds well to surgical management, with newer technology, such as sialendoscopy, potentially reducing the need for gland removal in these cohorts. Infectious pathologies, particularly MAC, require careful consideration as to when to operate given the risk of complication when undertaking gland removal in these regions.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://www.theajo.com/article/view/10.21037/10.21037/ajo-24-39/rc

Data Sharing Statement: Available at https://www.theajo.com/article/view/10.21037/ajo-24-39/dss

Peer Review File: Available at https://www.theajo.com/article/view/10.21037/ajo-24-39/prf

Funding: None.

Conflicts of Interest: All authors have competed the ICMJE uniform disclosure form (available at https://www.theajo.com/article/view/10.21037/ajo-24-39/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring the questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Ethics approval was sought and approved by the Human Research and Ethics Committee (HREC) at The Royal Children’s Hospital Melbourne (QA/93034/RCHM-2023). Because of the retrospective nature of the research, the requirement for informed consent was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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