An Unusual Large Submandibular Gland Calculus: A Case Report

Abstract

Salivary gland stones (Sialothiasis) most commonly occur in the Submandibular duct. This report describes the case of a patient who had an unusual large submandibular gland sialolith (calculus) that was completely obstructing the submandibular gland duct.

Key words: Calculi, Giant salivary gland stones.

Introduction

The great majority of salivary calculi (80%) occur in the submandibular gland and in the duct. Ten percent occur in the parotid and the remaining 10% in the sublingual gland and the minor salivar glands.1
Bilateral or multiple-gland sialolithiasis is occurring in fewer than 3% of cases.2
In patients with multiple stones, calculi may be located in different positions along the salivary duct and gland.
Submandibular stones close to the hilum of the gland tend to become large before they become symptomatic. Sialolithiasis occurs equally on the right and left sides.
Commonly, Sialoliths measure from 1 mm to less than 1 cm. Giant salivary gland stones (GSGS) are those stones measuring over 1.5 cm and have been rarely reported in the medical literature.3,4 GSGS measuring over 3 cm are extremely rare, with only scanty reported cases.5

Case report

In 2010, a 53-year-old white male was referred to the Oral and Maxillofacial Surgery Department at Damascus General Hospital. He complained of a large, firm mass in the left side of the floor of his mouth in the submandibular gland area. He had a history of having episodes of left submandibular swelling occurring with meals. The past medical history was unremarkable.

Upon examination, bimanual palpation of the swollen area corresponding to the anatomic location of the left submandibular salivary gland duct further indicated that the mass was mobile, firm and non-tender (Figure1). The floor of the mouth was swollen. OPG revealed a large calcified mass at that area (Figure 2).A CT (Computerized tomography) scan showed a 3.32*1.14cm calculus blocking the submandibular gland duct (Figures 3, 4 and 5). Findings on blood and serum biochemistry were within normal limits.

Under local Anesthesia, the Calculus was excised via incision in the floor of the mouth and directly over the palpable mass. (Figure 6 and 7). The yellowish calculus was oval and had a rough, irregular surface (Figure 8). A short polyethylene tube was inserted at the site of incision. The flab was sutured around the tube (Figure 9). The sutures and the tube were removed after 2 weeks.

Discussion

The great majority of salivary calculi (80%) occur in the submandibular gland and in the duct. Ten percent occur in the parotid and the remaining 10% in the sublingual gland and the minor salivar glands.1 Flow of saliva against gravity, its more alkaline pH, and the high mucin and Ca+ content could explain the preferential stone formation in the submandibular gland.6 The exact etiology and pathogenesis are still unknown. There is a slight predilection for occurrence in men, usually above the age of 40 years.7 Patients present with pain, discomfort, and swelling before or during meals. Recurrent submandibular swelling is often mentioned. Bimanual massage of the affected gland and the excretory duct should be carried out, observing the flow and the clearness of the saliva. The calculus can often be located in the excretory duct, often quite anterior. This characteristically causes pain. Submandibular gland calculi have been reported to be radiopaque in 80% to 94.7% of cases.8, 9, 10 In the anterior floor of the mouth, an occlusal radiograph may reveal the calculus. Ultrasonography is widely reported as being very helpful in detecting salivary stones. As many as 90% of all stones larger than 2 mm can be detected as echodense spots on Ultrasonography.11 However, detection of small calculi may be difficult with ultrasonography. Computed tomography (CT) is also highly diagnostic.12
When located in the submandibular gland itself a panoramic radiograph may be helpful. In small and radiolucent calculi radiographic findings may be negative and sialography can be the examination of choice, although displacement of the calculus toward the gland cannot always be avoided.
Although large sialoliths have been reported both in salivary glands and in salivary ducts, stones larger than 3 cm are rare.8,13,14 The giant siaolith in this patient was completely encased in the duct of the submandibular gland. A review of the literature by Ledesma-Montes et. al found only 16 reported cases of stones having a size or 3.5 cm or greater.5
Sialoliths are ovoid or round, smooth or rough with a yellowish color. They consist of calcium phosphate with small accounts of hydroxyapatite, magnesium, potassium and ammonia.10
Submandibular stones are typically removed surgically via either an intraoral or an external approach.15, 16 Surgical removal of the calculi is performed when located in the excretory duct near the opening. If the calculi are located in the gland itself, fragmentation can be performed by extracorporal or endoscopic laser lithotripsy.17-19 This treatment has to be performed several times. After operative removal or lithotripsy of calculi, scintigraphic examination shows functional recovery of the gland. In a non-functioning gland surgical removal would be indicated to avoid recurrent disease. In many units removal of the gland may be the first choice of treatment.
The future holds great promise due to the developments of non-surgical, non-invasive techniques such as shock wave lithotripsy, basket retrieval, and endoscopic laser lithotripsy.20,21
In a review of over 4,691 patients, Iro, et al.21 reported that retrieval of stones by baskets or microforceps is usually done for stones less than 5 mm and extracorporeal lithotripsy was mainly used for fixed parotid stones that were less than 7 mm in diameter.21

Conclusion

This case highlights a rare case of large Calculus which can be avoided by early diagnosis and proper treatment. Once the diagnosis of a salivary gland stone is established attempts at removal by minimally invasive techniques should be considered.