|Year : 2012 | Volume
| Issue : 2 | Page : 137-142
Giant Sialolith in the Wharton's duct causing sialo-oral fistula: A case report and review of literature
Harish Saluja1, Vikrant O Kasat2, Uma Mahindra1
1 Department of Oral and Maxillofacial Surgery, Rural Dental College, Loni, Maharashtra, India
2 Department of Oral Medicine and Radiology, Rural Dental College, Loni, Maharashtra, India
|Date of Web Publication||17-Jan-2013|
Vikrant O Kasat
Department of Oral Medicine and Radiology, Rural Dental College, Loni - 413 736, Maharashtra
Source of Support: None, Conflict of Interest: None
Sialolithiasis is the most common salivary gland disease accounting for more than 50% of the cases. Majority of salivary calculi occur in the submandibular gland and its duct. It has male predilection and is often seen in adults. Majority of the calculi are less than 10 mm in size. Calculi > 15 mm in size are considered giant. Giant sialoliths within the parenchyma of the salivary glands are frequently reported in the literature, but they are uncommon in the salivary ducts. The purpose of this article is to report a case of giant sialolith in the Wharton's duct of a 65-year-old male, which had caused sialo-oral fistula. Literature in English language on "giant sialolith in Wharton's duct" is reviewed since 1990. Also etiology, pathogenesis, clinical features, diagnosis and management aspects are discussed.
Keywords: Calculus, giant, salivary gland, sialolith, submandibular duct, Wharton′s duct
|How to cite this article:|
Saluja H, Kasat VO, Mahindra U. Giant Sialolith in the Wharton's duct causing sialo-oral fistula: A case report and review of literature. J Orofac Sci 2012;4:137-42
|How to cite this URL:|
Saluja H, Kasat VO, Mahindra U. Giant Sialolith in the Wharton's duct causing sialo-oral fistula: A case report and review of literature. J Orofac Sci [serial online] 2012 [cited 2017 Sep 22];4:137-42. Available from: http://www.jofs.in/text.asp?2012/4/2/137/106214
| Introduction|| |
Sialolithiasis is a pathological condition caused by the obstruction of a salivary gland or its excretory duct by a calculus.  It is the most common salivary gland disease accounting for more than 50% of the cases. , It has an incidence of about 0.012% in the adult population.  It may occur at any age but there is a peak incidence in fourth, fifth and sixth decades.  It is uncommon in pediatric population accounting for only 3% of all sialolithiasis cases.  Males are affected more as compared to females with male: female ratio ranging from 5.5:4.5 to 7:3.  Majority of salivary calculi (80%-95%) occur in the submandibular gland, whereas only 5% to 20% are found in the parotid gland. The sublingual gland and minor salivary glands are rarely affected (1%-2%).  When minor salivary glands are involved, the most common sites are buccal mucosa or upper lip, and it presents as a firm nodule that may mimic tumor.  Simultaneous involvement of more than one salivary gland is rare. 
In general, sialoliths are common in submandibular duct compared to glandular parenchyma.  However, giant sialoliths are more common within the parenchyma of the salivary glands. Sialoliths located in the duct are usually elongated, while those situated in the gland or hilus tend to be round or oval.  Though bilateral cases have been reported (3%), salivary calculi are usually unilateral and occur equally on right and left sides.  Single sialolith is found in majority of cases (70-80%), two in about 20% of cases and three or more in 5% of patients.  They are usually yellowish in color and consist of mainly calcium phosphate with small amounts of carbonates in the form of hydroxyapatite, as well as smaller amounts of magnesium, potassium, and ammonia. Submandibular stones are composed of 82% inorganic and 18% organic material, whereas parotid stones are composed of 49% inorganic and 51% organic material.  Sialolithiasis typically presents as a painful swelling of the affected gland during mealtimes, because the stone usually does not block the flow of saliva completely. , However, most salivary stones are asymptomatic. 
Sialoliths commonly measure between 5 and 10 mm in size, and stones over 10 mm can be reported as sialoliths of unusual size.  Lustman in a study on 245 patients with sialolithiasis found that 78.8% were less than 10 mm in size, 13.6% were between 10-15 mm and only 7.6% were > than 15 mm in size.  Calculi > 15 mm in size are considered giant sialoliths.  Although, giant sialoliths have been frequently reported in the body of the salivary glands, they are rare in the duct of salivary gland.  The purpose of this article is to report a case of giant sialolith in the Wharton's duct and to review the related literature. A search of "PubMed" and "Google scholar" was made with the keywords "giant sialolith in the Wharton's duct," "megalith in the Wharton's duct," "salivary duct calculus," "sialolith in the duct of mandibular gland." It was supplemented with hand search to identify related published articles in dental journals. For review, only those articles published from 1990 onwards in English language with the sialolith present in Wharton's duct and having size > 15 mm were selected. From review it is clear that megaliths in the Wharton's duct are rare and as far as we could determine only 29 cases have been reported in last 22 years [Table 1].
|Table 1: Summary of case reports of giant sialolith in the Wharton's duct in chronological order|
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| Case Report|| |
A 65-year-old male reported to the Dept. of Oral Medicine and Radiology, with the chief complaint of pain and swelling in the floor of mouth on right side since eight months. Detailed history revealed that it started as small swelling which used to increase before meals eight months back. It gradually increased over next three months and then it burst leaving a yellowish white mass in the right floor of mouth which was noticed by patient. Patient experienced pain, as well as pus discharge from that region.
Intraoral examination revealed a well defined round swelling of approximately 2 × 1 cm in size in the floor of the mouth in relation to lower right second premolar and first molar. Overlying mucosa was normal in color except in the distal most part of swelling where there was break in continuity exposing the underlying yellowish mass. It was hard in consistency and tender on palpation [Figure 1]. A provisional diagnosis of sialolith in the right submandibular gland duct was made.
|Figure 1: Intraoral photograph showing sialolith in the floor of the mouth on right side causing sialo-oral fistula|
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Radiographic evaluation included cross sectional mandibular occlusal view and orthopantomogram [OPG] which revealed a large well defined oval homogenous radiopacity in the floor of the mouth on right side [Figure 2] in relation to lower right second premolar and first molar [Figure 3]. It was approximately 2.1 × 1.4 cm in size.
|Figure 2: Mandibular occlusal view revealing homogenous radiopacity in the floor of the mouth on right side|
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|Figure 3: Orthopantomogram showing a well defined radiopacity in relation to lower right second premolar and first molar|
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Patient was referred to Maxillofacial Surgery Department where sialolith was enucleated under local anesthesia. The preexisting sialo-oral fistula was extended in antero-posterior direction to the required length and blunt dissection was done to enucleate lesion in toto [Figure 4] and [Figure 5]. The healing was uneventful.
| Discussion|| |
The exact etiology and pathogenesis of salivary calculi is unknown. However, salivary stagnation, increased alkalinity of saliva, infection, inflammation or physical trauma to salivary duct or gland may predispose to calculus formation. , Commonly they are thought to occur as a result of deposition of the tricalcic phosphate salts around a nidus that consists of altered salivary mucin, desquamated epithelial cells and bacteria.  It is suggested that bacterial toxins produce a local environment with pH less than 5.5 leading to tissue damage; and when 7.2 pH is re-established during the healing process, crystallization of salivary ions (especially calcium phosphates) occurs leading to calculus formation.  According to another theory an unknown metabolic phenomenon increases the salivary bicarbonate content, altering calcium phosphate solubility and leading to precipitation of calcium and phosphate ions.  A retrograde theory states that substances or bacteria within the oral cavity migrate into the salivary ducts and become the nidus for further calcification.
The age in the cases reviewed ranged from 25 to 75 years with average of 46.7 years. Among the cases reviewed, majority occurred (26/29) in patients over the age of 40 years. None of the giant sialolith was seen in children which is consistent with the literature on sialolith. Among the 29 case reports summarized in [Table 1], the incidence is higher in men (n = 22) compared with women (n = 7) with male to female ratio of 3.1:1. Size of the sialolith in the reported cases ranged from 15mm to 72 mm. The sialolith presented by Rai  is perhaps the largest ever reported calculus in Wharton's duct (72 mm). The ability of a calculus to become giant depends mainly on the reaction of the affected duct. If the duct adjacent to the sialolith is able to dilate allowing nearly normal salivary flow, it might remain asymptomatic for a long period; thus eventually creating a giant calculus.  Weight of the giant sialolith was reported in only 6 cases, which varied from as light as 1.34 gm  to as heavy as 45.8 gm.  Duration of the sialolith was reported in 15 cases which ranged from 1 week to 22 years. It is believed that a calculus may enlarge at the rate of approximately 1 to 1.5 mm per year.  Thus, it is possible to explain the long duration of sialolith in few cases. In 16 cases it affected left side whereas right side was affected in 9 cases. Thus, it appears that giant sialolith has affinity for left side. However, in the present case right side was affected. Pain and swelling was the most common symptom in the reviewed cases. Sialolith causes pain and swelling of the involved salivary gland by obstructing the food related surge of salivary secretion.  The severity of symptoms depends on the degree of obstruction. In few cases patients were asymptomatic. ,,,
The submandibular gland is more susceptible to the development of the salivary calculi because its duct is longer and tortuous, salivary flow is against gravity, salivary pH is more alkaline and its saliva has greater content of mucin, proteins, calcium, as well as phosphates. , Generally, the most common radiographic techniques to diagnose submandibular sialoliths are panoramic and occlusal views.  Giant sialoliths are mostly radiopaque and are easily depicted on panoramic radiographs, probably because their lithogenesis is long enough for calcification to be completed.  Investigations like sialography, ultrasonography, and computed tomography may be required to locate small sialoliths (as 20% to 30% are radiolucent). ,, However, sialoliths smaller than 3 mm may not be detected during ultrasonographic examination, as they will not produce acoustic shadows.  Magnetic resonance sialography is a newer diagnostic modality that allows for visualization of the ducts without any radiation or dye injection, but it is limited by its cost and feasibility in claustrophobic patients.  Sialoendoscopy is a new, minimally invasive technique developed for direct visualization of intra-ductal stones. , In this report, as the lesion was observed clearly on occlusal and panoramic radiographs, no further investigations were performed for diagnosis.
Giant calculi may cause various complications. They may perforate the floor of the mouth by ulcerating the duct or may result in a fistula by causing a suppurative infection.  Perforation of the floor of the mouth is more likely to occur when calculus is present in anterior part of duct.  In our case, calculus had extruded in the floor of mouth causing sialo-oral fistula. Similar finding was reported by El Gehani, Akimoto, Patil, Huber, Shetty; whereas Paul and Chauhan reported sialo-oral as well as sialo- cutaneous fistula caused by sialolith. ,,,,, Also, long term obstruction in the absence of infection can lead to atrophy of the gland with resultant lack of secretory function and ultimately fibrosis.  However, after elimination of the obstruction, the apparent resiliency of the submandibular gland results in no adverse symptoms.  Consuegra reported two cases of giant sialolithiasis within the Wharton's duct causing unilateral absence of submandibular gland due to complete acinar atrophy. The submandibular glands were replaced by fat in the computed tomography images.  Association of sialolith with systemic diseases is questionable. Lustmann in a study on 245 patients with sialolithiasis found that 10.7% patients had associated nephrolithiasis.  Gout is the only systemic diseases known to predispose to salivary stone formation, although in gout the stones are predominantly made up of uric acid.  The differential diagnosis of sialolith includes calcified lymph node, embedded tooth, foreign body, phlebolith, and myositis ossificans. 
The treatment objective for giant sialoliths, as for the standard-sized stones, is restoration of normal salivary secretion. , Treatment approach for sialolith depends on its size and location. ,, Removal of stones through an intraoral approach is recommended whenever stones can be palpated intraorally. ,, If the stone is small and sufficiently forward it can be milked and manipulated through the duct orifice. , However, if the calculus is of a medium or large size, like the giant salivary gland calculi, a salivary colic may occur and the sialolith cannot be expelled spontaneously.  Almost half of the submandibular calculi lie in the distal third of the duct and are amenable to simple surgical release through an incision in the floor of the mouth. 
Newer minimally invasive treatment modalities such as shock-wave lithotripsy, sialoendoscopy, interventional radiology are effective alternatives to conventional surgical excision for smaller sialoliths (<7 mm).  Sialolithotripsy is a non-invasive method of fragmenting salivary stones into smaller portions in order to favor their possible flushing out from the salivary duct system spontaneously or after salivation induced by citric acid or other sialogogues. The shock-waves may be generated extra-corporeally using piezoelectric and electromagnetic techniques or intra-corporeally using electro-hydraulic, pneumatic or laser endoscopic devices.  In intra-corporeal lithotripsy, the shock-waves reach the stone surface through a lithotripsy probe placed inside the salivary duct system under endoscopic guidance.
In the early 1990s, salivary duct endoscopy or sialendoscopy emerged.  For sialoendoscopy flexible, rigid, and semi-rigid endoscopes have been used with outer diameters ranging from 0.8 to 2.7 mm. All of these sialoendoscopes have a working channel that allows the introduction of graspers, microforceps, Dormia baskets or balloon catheters for the removal of single or multiple stones.  The sialendoscopes also have an optic channel that transmits the image using fiberoptic channels and an irrigation channel allows a continuous irrigation to be performed to maintain duct patency for endoscopic visualization of the salivary duct lumen. However, the major limitation of sialoendoscopy alone is the difficulty in removing stones with a diameter > 4 mm.  Intermediate size stones between 5-7 mm may need further fragmentation either using a Holmium laser or lithotripsy prior to endoscopic extraction. Fluoroscopically guided stone retrieval with Dormia baskets and sialolithectomy with carbon dioxide laser are other special methods for removal of the calculus.  Retrieval of stones by baskets is usually done for stones less than 5mm.  The CO 2 laser is set up in continuous mode at 4-6W with a focusing spot. It has a low incidence of complications and can be readily managed on an out-patient basis.  However, for giant sialoliths, transoral sialolithotomy with sialodochoplasty or sialadenectomy remains the mainstay of management. ,, Akimoto reported an interesting and only case of a giant sialolith in which the calculus was not extracted surgically, but patient himself removed the calculus. The patient could easily pull it out because it was long, extremely narrow and its tip had perforated floor of the mouth. 
In some cases, excision of the entire gland is required. Submandibular gland removal is indicated if 1) the gland has been damaged by recurrent infection and fibrosis, 2) there is a stone of substantial mass within the gland itself that is not surgically accessible intraorally, 3) there are small stones present in the vertical portion of Wharton's duct from the comma area to the hilum, 4) the size of an intraglandular stone reaches 12 mm or more as the success of lithotripsy may be less than 20% in such cases. ,,
Lustmann  in a survey on 245 patients with sialolithiasis for 20 years (1968-188) found a recurrence rate of 8.9% for a follow-up period of 10 years, which is higher than reported in literature. A diet rich in proteins and liquids including acid food and drinks is advisable in order to prevent recurrence. 
| Conclusion|| |
The diagnosis of giant sialolith in the Wharton's duct is further simplified when it presents as a hard mass in the floor of mouth causing sialo-oral fistula. Transoral sialolithotomy remains mainstay of the treatment for giant sialolith in the duct of submandibular gland. Also, patients should be followed up regularly as recurrence has been reported in the literature.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]