Facial cellulitis caused by Giant parotid sialolith: a minimally invasive treatment for a rare occurrence

Sialolithiasis is a common disease that affects the major salivary glands and can occur at any age. Parotid glands are rarely involved and, even rarer are the cases of sialoliths larger than 10 mm. This report presents the rare case of a giant parotid sialolith associated with facial cellulitis in a 75-year-old man. The treatment involved initially nonsurgical approach followed by a minimally invasive surgery to restore health and function. The treatment protocol was completely successful and proved effective in clinical and surgical management of giant parotid sialolith associated with facial cellulitis.


Introduction
Sialolithiasis is a common disease that affects the major salivary glands. It is characterized by obstruction of salivary secretion by a calculus, commonly associated with swelling, pain and infection of the affected gland Bodner, 1993;Bodner, 1999). Submandibular gland is the most affected gland (80% to 95%), whereas 5% to 20% are found in the parotid gland.
The sublingual gland and the minor salivary glands are rarely affected (1% to 2%). Sialoliths can occur at any age, but there is a peak incidence between the third and sixth decades and a male predilection is reported (Lustmann, Regev, & Melamed, 1990;Bodner, 2002).
Sialoliths are mostly composed by calcium phosphate (hydroxyapatite) and also an organic matrix consisting of carbohydrate and amino acids. The mechanism of the formation of sialoliths is still poorly understood, although the pH, mucin content, high Ca++ concentration of the gland, salivary stagnation, a nidus and a precipitaion of salivary salts. Furthermore, the ascendant, snaky rout and against gravity long lenght of the Wharton's duct can also contribute, probably explaining the higher rate of occurrence in this gland. Infection, inflammation of the gland, or physical trauma to the duct or its orifice are also listed as predisposing factors (Bodner, 1993;Bodner, 2002;Guastaldi, da Silva, Troulis, & Lahey, 2018).
The present article is a report on an unusual giant parotid sialolith as a cause of facial cellulitis, its diagnosis and management.

Methodology
A descriptive and qualitative interventional study was carried out, in the format of a Case Report of a patient's followup during treatment. The epidemiological data and, history of the disease, were collected through the physical and electronic records, after authorization of the patient and signature of the Informed Consent, as (Brown et al, 2016).

Case Report
A 75-year-old man was referred to the emergency, with a two-week history of fever and a painful, diffuse tender swelling on the right side of the face (Figure 1). He reported intermittent episodes for 5 years of moderate to severe pain and swelling which settled spontaneously or with a course of oral antibiotics. He referred diabetes mellitus and systemic arterial hypertension, controlled by oral metformin and captopril, respectively. There was no history of tooth pain during all of this period, what would reinforce the diagnosis of a non-odontogenic cellulitis.   Research, Society andDevelopment, v. 10, n. 3, e58210313754, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i3.13754 5 Considering the patient`s clinical conditions, we opted for hospitalization and intravenous antibiotic therapy for initial control of infection and subsequent sialolith surgical removal. The antibiotic therapy consisted of intravenous ceftriaxon (1g, twice a day), metronidazole (500mg, three times a day) and gentamicin (80 mg, three times a day). After 5 days, the swelling, pain and trismus were better and the surgery was performed under general anesthesia (Figure 4).  A small amount of purulent mucous saliva was discharged after reaching the Stensen`s duct surgically and the sialolith was removed afterwards. The sialolith measured 16 X 12 mm ( Figure 6).

Discussion
Parotid sialoliths are considered rare as compared to those of the submandibular gland. The presence of microcalculi in 80 % of normal submandibular and only in 10 % of normal parotid glands may explain the differences of sialoliths incidence in these two glands (Bodner, 1999;Epivatianos, & Harrison, 1989).
The higher incidence of sialolithiasis in elderly patients may be due medication consumption that would reduce the secretory activity, modify electrolyte saliva concentrations and glycoprotein synthesis leading to structural deterioration of cell membranes of the salivary glands (Lustmann et al, 1990;Bodner, 2002;Bodner & Gorsky, 1996).
This case is an acute exacerbation of a longstanding chronic asymptomatic parotid sialolithiasis, mimetizing an odontogenic cellulitis. The sialolith large size (16 x 12 mm) indicates a rare giant parotid sialolith, one of the largest parotid sialolith ever reported. Igbal et al. (1992) reported a parotid calculus measured 30 X 25 X 15 mm. Kesse et al. (1998) reported a giant parotid calculus measured 50 mm in length and 30 mm in its longest width, the largest parotid gland calculus ever reported. Bodner (1999) reported another giant parotid calculus measured 25x13mm. Bodner (2002) showed that only 14 welldocumented cases of Giant salivary gland calculi (>15 mm) have been reported in the literature since 1942, involving submandibular and parotid gland, being a quite rare occurrence in the parotid gland with only 2 cases reported in that survey.
The treatment objective of giant sialoliths, as for the standardsized stones, is restoration of normal salivary secretion. However, differential diagnosis is essential in cases of orofacial infections. Odontogenic infections usually present themselves as cellulitis. So the precise source of infection must be detected and the less invasive treatment as possible applied to avoid the morbidity caused by sialadenectomy, as usually required in cases of intraglandular sialoliths (Bodner, 2002).

Conclusion
In the case presented, the intraductal location and the favorable clinical evolution after antibiotic therapy avoided the need for extraoral drainage, sialedenectomy and other anti-aesthetic and invasive approaches, proving to be a successful treatment protocol for this rare occurence.