Keywords
salivary gland - fistula - submandibular gland
Introduction
Branchial fistulas are the most common differential for a lateral neck fistula.[1] Salivary gland fistulas are relatively less common and are mostly limited to the parotid gland.[2] A submandibular gland fistula (SGF) is extremely rare and can often be clinically confused with branchial fistula and other close differentials.
Various etiologies have been attributed to SGF, including both congenital and acquired.[3]
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[18] The clinical manifestation of SGF varies and is influenced by the etiology of the disease, making it tough for clinicians to diagnose it clinically. Furthermore, the site of the fistula opening has been shown to have an effect on the clinical features.
Certain clinical clues and radiological findings can help achieve a confirmatory diagnosis even prior to surgical exploration or histopathological examination. This will aid clinicians in optimal surgical planning and avoid irrelevant investigations/interventions.
Methods
A comprehensive review of the literature was performed using PubMed and Google Scholar database in September 2022 and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards ([Fig. 4]). The database was searched for full-length articles using a combination of keywords, submandibular gland fistula, AND submandibular fistula, AND submandibular AND fistula and compatible with submandibular gland/duct fistula. The content of each article was reviewed in order to identify the studies relevant to the topic. Cases with fistulae arising from aberrant/ectopic glands were excluded. Only articles published in English literature and confined to humans were included. No age limits were applied. Information from the included articles and an illustrative case were collected in a predesigned Microsoft excel spreadsheet (Microsoft Corp., Redmond, WA, USA). Continuous variables were summarized with mean and standard deviation (SD). Nominal variables were summarized with frequency and percentage. No other statistical tests were done.
Fig. 4 Literature search flow diagram based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards.
Result
A total of 18 cases (17 cases from 16 published articles and an illustrative case) were included in the current review ([Tables 1] and [2]).[3]
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[18] The age ranged from 6 to 72 years. The exact numerical age was not mentioned in two cases reported by Keiliszak et al. Of the remaining 16 cases, the average age was 39.75 (SD: 20.93) years. There were 12 males and 6 females (male/female ratio: 2/1). Calculi/foreign body (50%) and trauma (22.2%) were the 2 most common associated etiologies. Most fistulae had opening at the cervical cutaneous site (61.1%) followed by the mucosa of the floor of the mouth (16.7%).
Table 1
Summary of cases of submandibular gland fistula
|
AuthorRef. #
|
Year
|
Age (years)
|
Sex
|
Cause
|
Opening
|
Treatment
|
|
Geus et al.[3]
|
1976
|
8
|
Male
|
Trauma (electric current)
|
Neck skin
|
Gland and fistula tract excision
|
|
Knezević et al.[4]
|
1983
|
14
|
Male
|
Foreign body
|
Neck skin
|
Excision of external sinus & removal of glass
|
|
McFerran et al.[5]
|
1993
|
41
|
Female
|
Congenital
|
Oropharynx
|
Observation- spontaneous regression
|
|
Paul et al.[6]
|
1995
|
45
|
Male
|
Calculi
|
Neck skin and floor of mouth
|
Removal of sialolith and sialo-cutaneous fistula tract
|
|
Singh et al.[7]
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1995
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41
|
Male
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Trauma (gunshot)
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Neck skin
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Spontaneous resolution with conservative management
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Obaid et al.[8]
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2000
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49
|
Male
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Calculi
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Floor of mouth
|
Conservative management
|
|
Durgun et al.[9]
|
2003
|
60
|
Female
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Congenital
|
Neck skin
|
Gland and fistula tract excision
|
|
Jana et al.[10]
|
2006
|
10
|
Male
|
Trauma
|
Neck skin
|
Gland and fistula tract excision
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Saha et al.[11]
|
2012
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54
|
Male
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Calculi
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Neck skin
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Gland and fistula tract excision, calculi excised
|
|
Saluja et al.[12]
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2012
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65
|
Male
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Calculi
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Floor of mouth
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Calculi excision and suture repair of fistula opening
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Rangappa et al.[13]
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2014
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55
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Female
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Calculi
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Neck skin
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Gland and fistula tract excision, calculi excised
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Keiliszak et al.[14]
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2015
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20s
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Male
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NK
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Submucosal floor of mouth
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Gland excision
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Keiliszak et al.[14]
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2015
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20s
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Male
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Calculi
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Floor of mouth
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Gland and fistula tract excision, calculi excised
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Kulkarni et al.[15]
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2015
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45
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Male
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Malignant tumor
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Neck skin
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Radical submandibular gland excision, segmental mandibulectomy and modified radical neck dissection.
|
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Kusunoki et al.[16]
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2017
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72
|
Male
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Calculi
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Neck skin
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Gland and fistula tract excision, calculi excised
|
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Stegmann et al.[17]
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2018
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6
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Female
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Calculi
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Neck skin
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Sialendoscopic removal of sialolith and sialo-cutaneous fistula tract excision
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Ha et al.[18]
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2019
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53
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Female
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Sialadenitis
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Subplatysmal neck site
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Conservative management with systemic antibiotic
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Present case
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2022
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18
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Female
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Trauma
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Neck skin
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Gland and fistula tract excision
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Table 2
Etiology, clinical findings, radiological features, and advocated treatment amongst the reported cases of submandibular gland fistula
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Variable
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Number (n)
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Frequency (%)
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Cause
•Calculi/ foreign body
•Trauma (gun shot, electric current, physical, iatrogenic)
•Congenital
•Malignant tumor
•Sialadenitis
•NIO/NK
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9
4
2
1
1
1
|
50
22.22
11.11
5.56
5.56
5.56
|
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Fistula opening site
•Isolated cutaneous neck
•Isolated floor of mouth
•Both cutaneous neck & floor of mouth
•Oropharynx
•Submucosal floor of mouth
•Subplatysmal neck site
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11
3
1
1
1
1
|
61.11
16.67
5.56
5.56
5.56
5.56
|
|
Clinical features
•Discharge from fistula opening
•Swelling / mass in submandibular region
•Tender/pain over submandibular region
•Throat lump
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12
10
8
1
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66.67
55.56
44.44
5.56
|
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Imaging modality advocated
•CT scan/ CT fistulography
•USG
•Xray
•Xray sialography/ fistulography
•OPG
•Barium swallow
•NP
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6
2
3
4
1
1
3
|
33.33
11.11
16.67
22.22
5.56
5.56
16.67
|
|
Radiological findings
•Fistula tract
•Calculi
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6
6
|
40 (6/15)*
66.67 (6/9)[□]
|
|
Treatment modality
Surgical
•Gland and fistula tract excision with/without calculi removal
•Gland preserving surgery (calculi/foreign body removal with fistula excision/repair)
Conservative management/ observation
|
14
10
4
4
|
77.78
55.56
22.22
22.22
|
Abbreviations: NIO/NK, no information obtained/ not known; NP, not performed.
*Total number of cases amenable to radiological investigations in which fistula were detected.
□ Total number of calculous causes of fistula in which calculi were detected radiologically.
Clinical symptoms/signs were present in the following frequencies: Discharge from fistula opening (66.7%), swelling/mass in the submandibular region (55.6%), tender/pain over the submandibular region (44.4%), and throat lump (5.6%). Three out of 12 discharging fistula cases (25%) had discharge symptoms that got aggravated while eating or when the patient was exposed to the smell/thought of food (Jana et al., Rangappa et al., and the present case). In the remaining nine cases, no relationship between discharge and food was mentioned or present. One case presented a sensation of throat lump that increased with stress (McFerran et al.).
Clinical manifestation varied with the site of fistula opening and associated etiology. External fistulae mostly presented with serous/mucoid/mucopurulent discharge from the opening, which can sometimes be related to food. Eleven out of a total of 12 patients (91.67%) with external cutaneous opening complained of discharging fistulae. Only one case of external cutaneous fistula did not mention symptom of discharge (Kusunoki et al.). Most patients with calculi/foreign body as etiology presented with obstructive complaints of pain/tenderness or swelling in the submandibular region. Out of 9 cases with sialolith/ductal foreign body, 7 (77.78%) presented with either both or isolated symptom of pain/tenderness and/or swelling over the submandibular site. The remaining two cases of calculi/foreign body only presented with discharge (Knezević et al. and Saha et al.).
Fifteen cases advocated various imaging modalities including plain radiogram, X-ray sialography/fistulography, orthopantomogram (OPG), barium swallow, ultrasonography (USG) and CT scan/CT fistulography. In the remaining three cases, no radiological investigation was done. In these 15 cases, a radiological diagnosis of fistula was made in only 6 patients (40%). Amongst the 9 cases with actual calculi, a radiological detection was made in 6 cases (66.7%).
Gland excision with removal of fistula and/or calculi was the most commonly advocated treatment (55.6%). Gland preserving surgery and conservative management were less commonly performed and both were utilized in 22.2% of cases.
Discussion
Submandibular gland fistula is a rare entity. It is associated with various acquired etiologies, including calculi, foreign body, trauma, neoplasm, sialadenitis, or a congenital process linked to the branchial apparatus.[3]
[4]
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It can be an external sialo-cutaneous fistula or an internal sialo-oral fistula. The external opening is either cutaneous or subcutaneous. Similarly, an internal fistula opening is either mucosal or submucosal.[3]
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[9]
[10]
[11]
[12]
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[18]
Clinical manifestation varies with the site of fistula opening and associated etiology. An external fistula mostly presents with serous/mucoid/mucopurulent discharge from the opening, which can sometimes be related to food. On the other hand, a fistula associated with calculi/foreign body mostly presents with obstructive or colicky complaints of pain/tenderness or swelling in the submandibular region.
Various authors have advocated different forms of management varying from observation and conservative management to surgical intervention, including either gland-preserving surgery or excision of the gland with fistulae tract.[3]
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[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
Final Comments
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The present systematic review highlights certain vital clinical and radiological clues that will aid in an early diagnosis of submandibular gland fistula even prior to surgical exploration.
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We believe that these diagnostic checkpoints will help clinicians achieve optimal management planning and avoid irrelevant investigations/interventions, especially in a resource-limited hospital setting.
