A case of giant sialolith of the submandibular salivary gland.

Abstract

Sialolithiasis is the most common disease of the salivary glands. This report describes the case of a patient who had an unusually large submandibular gland sialolith that was completely encased in the glandular substance. The author describes the management of this patient and reviews the literature.

Introduction

Sialolithiasis is the most common disease of the submandibular glands in middle-aged patients. (1) It is more common in males than females. (2) Calculi can form in any of the salivary glands of the head and neck, but the submandibular gland is the most common site (80 to 92% of cases). (3-5) Lower rates have been reported in the parotid gland (6 to 20%) and the sublingual and minor salivary glands (1 to 2%). (3-5) Factors that tend to favor submandibular vs. parotid gland stone formation are (1) the longer and larger caliber duct and slower flow rates in the submandibular gland compared with the parotid gland, (2) the tact that saliva flows against gravity in the submandibular gland, (3) the presence of more alkaline saliva in the submandibular gland, and (4) the high mucin and calcium content of the saliva in the submandibular gland. (6) Bilateral or multiple-gland sialolithiasis is uncommon, occurring in fewer than 3% of cases. (4) Also, 70 to 80% of cases feature solitary stones; only about 5% of patients have three or more stones. (4) Almost one-quarter of symptomatic submandibular salivary glands that harbor stones are hypofunctional or nonfunctional. (7) Sialolithiasis occurs equally on the right and left sides.

The submandibular gland hosts the largest stones. The largest reported stone was 55 mm in length. (8) Most submandibular stones are found in the salivary duct (75 to 85% of cases). (7,9) Submandibular stones close to the hilum of the gland tend to become large before they become symptomatic. In patients with multiple stones, calculi may be located in different positions along the salivary duct and gland. Stones in the hilum of the gland tend to be oval, whereas stones in the duct tend to be elongated. Their surface can be either smooth or irregular. (10)

Case report

A 56-year-old man came to the Department of Otolaryngology--Head and Neck Surgery with a huge, firm mass below the right angle of the mandible. Bimanual palpation of the right submandibular salivary gland further indicated that the mass was mobile and tender. Radiography revealed that a large calcified mass had arisen below the right mandible near the angle. Findings on blood and serum biochemistry were within normal limits.

The gland and the calculus were excised via an incision in the skin crease 2 cm below the lower border of the mandible and directly over the palpable submandibular gland. The gland with the calculus was dissected free, along with the associated lymph nodes, and the wound was closed in layers, with insertion of a vacuum drain.

The salivary gland measured 6 cm in its largest dimension, and the enclosed calculus measured 3 cm (figure). The creamy yellow calculus was round and had a rough, irregular surface. It weighed 6 grams. Microscopic evaluation of the gland revealed the presence of a chronic inflammatory process, with infiltration of lymphocytes in stroma and destruction of the acini. The presence of fibrotic tissue covering the gland was apparent, and the epithelial layer of the main duct was destroyed.

Discussion

Although large sialoliths have been reported both in salivary glands (11,12) and in salivary ducts, (13-16) stones larger than 3 cm are rare. (8,11,14,17) The giant siaolith (3 cm) in this patient was completely encased in the glandular substance.

Submandibular gland calculi have been reported to be radiopaque in 80 to 94.7% of cases. (5,7,18) Often, an anteroposterior view of the mouth will allow for visualization of the stones. Sialograms have been reported to be as much as 100% effective in detecting ductal and intraglandular calculi. (19) If the intraparenchymal ducts are dilated grossly and the smaller ducts are not filling in the sialogram, the physician should suspect that the gland is nonfunctional. (20)

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. (21) Computed tomography is also highly diagnostic, albeit more expensive. (22) Some authors have recommended that preoperative technetium-99m pertechnetate scintigraphy be obtained to determine how functional the gland is and thus to determine its treatment. (23)

Submandibular stones are treated surgically via either an intraoral or an external approach. The most appropriate mode of treatment depends primarily on the stone's location. Excision of the submandibular gland carries a 0 to 8% risk of permanent or temporary marginal mandibular nerve palsy. (24) Smith et al reported that when a low approach was used, no permanent marginal mandibular nerve palsy occurred, although 36% of nerves were temporarily dysfunctional. (25) The likely reason for this is that the nerve is stretched during the lower surgical approach to the gland. In the case described in this report, no permanent or temporary nerve palsy occurred.

Once the diagnosis of an intraglandular salivary stone with destruction of the gland is established, removal of the entire gland via an extraoral approach is recommended.

References

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