Definition and Epidemiology

The parotid gland is the largest of the three major salivary glands in the body. An inflammatory reaction of the parotid gland is defined as parotitis. This is not to be confused with sialadenitis, which is defined as the inflammation or infection of a salivary gland.¹ Parotitis may be caused by bacterial, viral, fungal, or mycobacterial invasion. The parotid gland is most commonly affected by an inflammatory process, and infections can range from acute to severe. Assessment of the disease process should differentiate between local primary infections of the parotid gland, such as bacterial sialadenitis, and systemic infection, in which the gland is inflamed from a generalized inflammatory process caused by a virus. Viruses most commonly associated with parotitis are the paramyxovirus (cause of mumps) and the human immunodeficiency virus (HIV).²

Inflammatory conditions of the parotid gland include acute viral inflammation, commonly caused by mumps, and acute suppurative sialadenitis, often caused by Staphylococcus aureas. Chronic inflammatory conditions of the parotid are caused by infection with Mycobacterium tuberculosis (tuberculosis [TB]) and HIV.³ Noninfective causes of parotitis can be related to Sjögren syndrome (SS) and sarcoidosis.³

Acute suppurative parotitis is more likely to be encountered in the sixth to seventh decade of life, with a higher incidence in men and with the right side involved more frequently than the left.² Older adults are at a higher risk of development of acute suppurative parotitis because of a medication-induced (e.g., anticholinergics and antihistamines) decrease in salivary flow.² Other factors are associated with acute suppurative parotitis. These include chronic illness (e.g., diabetes mellitus, hypothyroidism, renal failure, rheumatoid arthritis), an immunocompromised host, poor oral hygiene, salivary duct obstruction, autoimmune disease (SS), recent surgical procedure, radiotherapy, and hypovolemia.² Acute suppurative parotitis has been identified as a common postoperative occurrence in patients undergoing major abdominal and hip repair surgery.² This has been attributed to postoperative dehydration and is usually identified within the first 2 weeks after surgery.² Acute suppurative parotitis is rarer now because antibiotic use in the perioperative setting is more common and there is increased attention to perioperative hydration, nutrition, and oral hygiene.¹

Pathophysiology

The parotid gland is most susceptible to infection because it secretes serous saliva versus mucinous saliva.² Serous saliva lacks lysosomes, immunoglobulin A antibodies, and sialic acid, all with bacteriostatic properties, thus predisposing the parotid gland to a greater risk of infection compared with its counterparts.² Multiple factors contribute to the development of parotitis. Most commonly, the infection begins with retrograde migration of oral cavity flora through the Stensen duct. Stasis of saliva, ductal obstruction, decreased stimulation of saliva, decreased mastication, and poor oral hygiene contribute to retrograde migration.^2,4 Ill patients, recent surgical patients, and those with acute or chronic hypovolemia can develop stasis and retrograde migration. Although most of these infections occur in adults, they can occur in children also. Presentation of parotitis in the pediatric population is usually an isolated occurrence and associated with a viral or bacterial infection.⁵ Parotitis is also the classic symptom of infection with paramyxovirus (mumps).⁶

Clinical Presentation

Usually the onset of parotitis is rapid and associated with localized pain, edema, and induration of the infected gland.⁴ Systemic symptoms include fever, chills, anorexia, and malaise.⁴ Viral inflammatory reactions most often are seen with edema (usually bilateral) and pain, which is exacerbated by mastication.⁴ Parotitis associated with a bacterial infection (acute suppurative sialadenitis) often occurs in a hypovolemic elder and consists of unilateral parotid enlargement and cellulitis.³ Intraorally, pus can be visualized with manual pressure on the parotid duct orifice.⁴ Chronic inflammatory conditions of the parotid caused by the infective agent M. tuberculosis appear much like a malignant neoplasm, with enlargement of and pain in the affected gland.³ The mass is usually unilateral and associated with matted lymph nodes.³ Infection with HIV may produce bilaterally enlarged, painless parotid glands that gradually produce smaller amounts of saliva, resulting in complaints of xerostomia.³

Physical Examination

Bimanual palpation of the gland with attention to the Stensen duct should be performed. In bacterial parotitis, palpation of the gland elicits a suppurative discharge from the Stensen duct.² Bilateral edema is suggestive of viral infection, and a clear discharge is found on palpation of the duct. Suppurative discharge should be cultured. If the process has been present for several days, fluctuance of suppurative sialadenitis may not be palpable because of the anatomic septations in the parotid.