Sialolithiasis is one of the most common salivary gland disorders, most commonly affecting the submandibular gland. Submandibular sialolithiasis can be treated using non-invasive conservative measures and invasive treatments. Treatment selection was based on the ductal system anatomy and the size and location of the stones. This study aimed to review the updates on sialolithiasis treatment and compare the different management strategies of the variables.

This report presents a case of a long-term, rare, and giant sialolithiasis within the submandibular gland parenchyma for 30 years in an older adult. Our patient presented with painless right submandibular swelling. Computed tomography revealed a calcified mass measuring 35 mm × 20 mm within the right submandibular gland. In this case, the infection and fibrosis of the affected gland and size of the stone did not provide us with other alternatives except for the excision of the involved gland. Thus, right submandibular sialoadenectomy was performed via the transcervical approach. After the surgery, the patient recovered without any complaints, side effects, or complications.

Tailored management is important for preserving gland function, maintaining low risk, and reducing patient discomfort.

Sialoliths are calcified salivary stones that can form within the secretory system of the salivary glands. Although various hypotheses have been proposed, the exact etiology of these sialoliths remains unclear. Most patients with sialolithiasis present with symptoms such as local pain, focal swelling, trismus, xerostomia, and lumps in the throat. Inflammation with oozing pus may be noted in some cases due to secondary infection.

The submandibular gland is the most commonly affected site for sialoliths, accounting for approximately 80%-90% of cases[1]. The rate of giant sialolith formation within the submandibular gland is high, and several contributing factors have been proposed, including a longer Wharton’s duct, larger duct caliber, and tortuous course of the Wharton’s duct accompanied by a slower salivary flow rate within the submandibular gland compared with that in other salivary ducts. The slower salivary flow rate is caused by saliva in the submandibular glands flowing against gravity, and the dependent position of the gland makes it more prone to stasis. Additionally, owing to the higher calcium and phosphate levels, the saliva within the submandibular glands tends to be more alkaline and may induce sialolithiasis[2].

Sialoliths usually range from 1 mm to 10 mm in size, and those measuring 15 mm in one dimension are classified as giant sialoliths[3]. In this report, we present a case of giant right submandibular sialolithiasis that was treated by surgical ablation for approximately 30 years and compare various giant sialolith cases and their different treatments with respect to variables such as size, duration, and symptom presentation.

Combined with the patient’s medical history, the final diagnosis was submandibular sialolithiasis.

Excision of the right submandibular gland and sialoliths was performed using a standard extraoral approach. Intraoperative findings revealed that the right submandibular gland was indurated and filled with giant sialoliths. Neighboring structures, such as the hypoglossal, lingual, and marginal mandibular nerves, were preserved (Figure 2).

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Figure 2 Excised sialolith and right submandibular gland.

The postoperative was uneventful, with no complications. Histopathological examination confirmed the diagnoses of sialolithiasis and chronic sialadenitis. A giant, yellow, hard sialolith measuring 25 mm × 17 mm × 17 mm was noted. Microscopically, the submandibular gland showed varied dilatations of the salivary ducts (ductal ectasia). Ulcerative changes in the dilated ductal epithelium with areas of squamous metaplasia, periductal fibrosis, and moderately mixed acute and chronic inflammatory infiltrates with lymphocytic aggregate foci were also observed.

Several treatment modalities for submandibular sialolithiasis exist; however, the primary goal is to preserve gland function, maintain low risk, and reduce patient discomfort[4]. Non-invasive conservative measures for submandibular sialolithiasis include glandular focal massage and trans-oral removal. Glandular focal massage is important during or after the administration of sialagogues, and irrigation is primarily indicated in cases of small intraductal stones. Transoral removal can be considered if stones are palpated bimanually and/or localized within the perihilar region of the gland using ultrasonography[4,5]. If a superimposed infection is suspected, antibiotics should be prescribed and, when warranted, combined with simple sialolithotomy[5,6].

Invasive management of submandibular sialolithiasis consists of open surgery (which can be performed with transoral duct surgery[7-9] or a transcervical approach to the submandibular space[10], extracorporeal shock wave lithotripsy[11-15], interventional sialendoscopy, and intraductal shock-wave lithotripsy[16-19]. These invasive methods are recommended for stones > 7 mm with symptoms[20]. Treatment selection is mostly based on ductal system anatomy and the location of the stones[7].

Transoral duct surgery may be considered for stones of all sizes in the papilla, owing to the narrow ostium of the papilla and stones in the distal and middle ducts. Small mobile stones (not exceeding 3-5 mm) in the papilla distal and middle ducts can also be extracted using interventional sialendoscopy. The proximal duct, however, is curved and narrow; thus, interventional sialendoscopy is difficult to perform. In cases where the stones are immobile, impacted, palpable, or large, transoral duct surgery is recommended, although mechanical fragmentation or intraductal shockwave lithotripsy followed by fragment extraction is also an option. Intraparenchymal stones are rare; however, if small, mobile stones (not exceeding 3–5 mm) can be visualized during endoscopy, interventional sialendoscopy, including mechanical fragmentation or intraductal shock wave lithotripsy, is recommended. Transoral duct surgery with submandibulectomy is indicated for large palpable stones ( 10 mm) located posthilar to the intraparenchymal region. Finally, salivary gland massage combined with a sour diet and sialogogue use is recommended after the removal of salivary stones[5].

In summary, transoral duct surgery offers better accessibility to the duct system and remains the preferred treatment modality; however, intraductal shock wave lithotripsy has gradually replaced transoral duct surgery in cases of smaller salivary stones. Compared with an earlier algorithm for the management of submandibular stones published in 2009, the indications for extracorporeal shockwave lithotripsy have since been adjusted, and the newly developed intraductal shockwave lithotripsy is also available. Although extracorporeal shockwave lithotripsy is considered less important, the procedure remains an option for intraparenchymal stones that are not visible or accessible. Finally, botulinum toxin injections may be considered in situations where the patient is deemed inoperable[7].

Among all the invasive treatment methods, adenectomy has a higher success rate than other techniques. Open surgery via the transcervical approach has a lower risk of infection because the oral space does not communicate with the neck space, whereas the intraoral approach avoids facial scarring. However, open surgical approaches are associated with several complications. Examples include postoperative neurological damage, particularly hypoglossal, lingual, and marginal mandibular nerve injuries, hemorrhage, hematoma, and disfiguring scars. Temporary marginal mandibular nerve damage is the most common complication of transcervical submandibular gland surgery. This complication was reported to be 36% by Smith et al[21], and permanent damage was reported to be as high as 12% by De et al[22]. in the literature. Beahm et al[23] reported rates between 7.7% and 36% in a previous literature revie. To reduce the risk of marginal mandibular nerve injury in the transcervical surgical approach to the submandibular gland, three surgical maneuvers are recommended: (1) The gland was identified to be lower than the hyoid bone, and the marginal mandibular nerve was not examined; (2) The marginal mandibular nerve is located at the level at which it leaves, tracks, and protects the parotid tail; and (3) The facial veins are located at a lower level and ligated, and the nerve is suspended by elevation; thus, the marginal mandibular nerve is removed from the surgical area.

However, Smith et al[21] reported that when a lower approach was used, no permanent marginal mandibular nerve palsy occurred, although 36% of the nerves were temporarily dysfunctional. This may have been due to stretching during the lower surgical approach to the glands. The hypoglossal nerve is partially sheltered by the posterior belly of the digastric muscle, which is located in the inferomedial portion of the lower one-third of the submandibular glands. This may explain why hypoglossal nerve damage has been reported very rarely (0%-1.4%)[24] compared with marginal mandibular nerve injuries. In this case report, no permanent or temporary complications occurred during the postoperative follow-up. Although the submandibular glands contribute 69% of the salivary secretion volume in the resting state[25], xerostomia was not reported in our case. This could be explained by the fact that other salivary glands were sufficiently functional to compensate for the resected glands.

Moreover, regarding the oncological risk to which patients with chronic inflammation and lithiasis are exposed[26], we reviewed some studies on salivary gland tumors. Most salivary gland tumors arise in the parotid gland (70%), followed by the minor salivary glands (22%) and submandibular glands (8%)[27]. Differential diagnoses for benign submandibular tumors include pleomorphic adenomas, Warthin’s tumors, and oncocytomas. Histopathological characteristics can be used to distinguish between them. Pleomorphic adenomas are characterized by thick irregularly marginated capsules[28,29]. Oncocytomas have thin capsules and monomorphic oncocytes without mitosis or necrosis[29,30]. The lymphatic population is the most common cytology and histology of Warthin's tumor[28,29]. Histopathological examination of our patient did not reveal the above characteristics, and the characteristics of malignant transformation include local invasion into the muscular, perineural, and lymphatic structures, as well as microscopic features, including nuclear atypia, cellular polymorphism, mitoses, and focal necrosis, were absent too. Thus, salivary gland tumors were excluded.

Owing to the similarities in the clinical presentation of benign salivary tumors and submandibular sialolithiasis, radiological imaging is essential to distinguish between the two entities. Ultrasound is recommended for the initial assessment of salivary gland abnormalities; however, ultrasound is insufficient because information on the surrounding structures cannot be provided. Its accuracy in the identification of benign salivary lesions can be increased using elastography or contrast-enhanced ultrasound; however, the European Federation of Societies for Ultrasound in Medicine and Biology do not recommend contrast-enhanced ultrasound for the characterization of salivary gland lesions in clinical practice. Thus, further studies are required to investigate the diagnostic roles of contrast-enhanced ultrasound and elastography in the evaluation of salivary gland lesions. Corvino et al[26] described the utility of CT and magnetic resonance imaging in the initial staging, histologic grading of salivary gland malignancies, and preoperative planning. Positron emission tomography with F-18 fluorodeoxyglucose is useful for the evaluation and clinical management of head and neck lesions[26].

Giant sialoliths are rare and classified as those measuring 15 mm in one dimension[3]. We compared cases of giant sialoliths in the submandibular gland from 1981 to 2022 and their different treatments according to variables such as size, duration, and symptom presentation. The cases and their details are listed in Table 1.

Between 1981 and 2022, 44 giant sialoliths were noted. The mean giant sialoliths size is 34.70 mm (two cases were within the range of 15-19 mm; 14 cases within 20-29 mm; 15 cases within 30-39 mm; seven cases within 40-49 mm; three cases within 50-59 mm; one case within 60-69 mm and one case within the range 70-79 mm). The median duration of giant sialoliths was 2 years (11 cases were less than a year; 9 cases were within the range of 1-5 years; two cases were within 6-10 years; three cases were within the range of 11-15 years; two cases were within the range of 16-20 years; one case was within the range of 36-40 years; and 15 cases did not discuss the duration). Of the 43 tumors, 23 and 21 were located in the right and left submandibular glands, respectively. Of the giant sialoliths, 90.70% were surgically removed (incision or excision), either intra-orally or extra-orally (transcervical), whereas 9.30% were removed using other methods. The patients with giant sialoliths reported by Ben-Shoshan and Lacroixl[31] did not undergo any intervention. Akinyamoju and Adisa[32] and Rodrigues et al[33] removed the stones non-surgically. Brooks et al[34] reported that a patient declined any additional diagnostic measures and was lost at follow-up. No postoperative complications were observed in these cases.

Giant sialoliths are rare, and their longer durations have rarely been documented. This report presents a case of long-term, rare, and giant sialolithiasis within the submandibular gland parenchyma for 30 years in an older adult. Our patient presented with typical clinical and radiographic findings. In this case, the infection and fibrosis of the affected gland and size of the stone provided us with no other alternatives except for the excision of the involved gland. Thus, right submandibular sialoadenectomy was performed via the transcervical approach. After the surgery, the patient recovered smoothly without any complaints, side effects, or complications. Based on the comparative table, this is the second largest case with a long duration that we would like to share. This case highlights the importance of proper diagnosis and treatment. Clinicians are advised to tailor management according to the patient and to keep in mind that the primary goal should always be to preserve gland function, maintain low risk, and reduce patient discomfort.