Description

• Inflammation of the parotid gland caused by infection, systemic illnesses, mechanical obstruction, or medications
• Can be unilateral or bilateral, acute or chronic
• The parotid gland is the largest of the salivary glands, located lateral to the masseter muscle anteriorly and extending posteriorly over the sternocleidomastoid muscle behind the angle of the mandible.
• It produces exclusively serous secretions, which lack the bacteriostatic properties of mucinous secretions, making the parotid gland more susceptible to infection than other salivary glands.
• The parotid duct, also called the Stensen duct, pierces the buccinator muscle to enter the buccal mucosa just opposite the 2nd maxillary molar.
• The branches of the 7th cranial nerve or “facial nerve” bisect the gland into lobes.
• The parotid gland contains 3 to 24 lymph nodes.

Epidemiology

• Viral parotitis is the most common cause of parotitis in children; has decreased since the advent of the mumps vaccine
• Acute bacterial parotitis occurs more frequently in elderly, neonates (especially preterm infants), and postoperative patients.
• Juvenile recurrent parotitis (JRP) is the second most common inflammatory cause of parotitis in children in the United States; first episode usually occurs between 3 and 6 years.
• Chronic parotitis mainly affects adults, more often females. The average age of presentation is between 40 and 60 years.
• Chronic bilateral parotid enlargement is a common manifestation of HIV infection; for perinatally HIV-infected children, the average age of onset for parotid enlargement is 5 years.

Etiology and Pathophysiology

• Acute viral parotitis begins as a systemic infection that localizes to the parotid gland, resulting in inflammation and swelling of the gland. Viral pathogens:
  • Mumps, or paramyxovirus, has a predilection for the parotid gland and classically linked to parotitis.
  • Parainfluenza virus types 1, 2, and 3; influenza A; coxsackievirus; Epstein-Barr virus (EBV); human herpesvirus (HHV6)
  • Cytomegalovirus (CMV) and adenovirus have been seen in patients with HIV.
  • Case reports demonstrate that parotitis can be a clinical manifestation of SARS-CoV 2 infection.
• Nonviral infections results from stasis of salivary flow that allows retrograde introduction of bacterial pathogens into the gland. Common pathogens:
  • Staphylococcus aureus and anaerobes (oral flora) most commonly
  • Streptococcus pneumoniae, viridans streptococci, Escherichia coli, and Haemophilus influenzae (less common)
  • Other gram-negative rods, such as Klebsiella, Enterobacter, and Pseudomonas, can be seen in chronically ill or hospitalized patients.
  • Bartonella henselae in patients with cat exposure and manifestation of late-onset group B Streptococcus
  • Fungal infections include Candida (chronically ill or hospitalized patients) and Actinomyces in patients with a history of trauma or dental caries.
• Recurrent parotitis etiologies:
  • JRP may be secondary to chronic inflammation; etiology is unknown, but a genetic predisposition may exist.
  • Mechanical: Repeated sialolith formation leads to ductal wall damage, fibrosis, and stricture formation.
  • Pneumoparotitis may occur when air is trapped in the ducts of the parotid gland; seen in wind instrument players, glass blowers, scuba divers, and with dental cleaning
  • Certain medications and chronic diseases (see “Risk Factors”) predispose to chronic parotitis.
  • Pediatric considerations include case reports of acute parotitis as a symptom of Kawasaki disease.

Risk Factors

• Lack of mumps, measles, rubella (MMR) vaccination
• Conditions that predispose to salivary stasis, such as dehydration, debilitation, poor oral hygiene, Sjögren syndrome, cystic fibrosis, bulimia/anorexia, sialolithiasis (stones), ductal stenosis, trauma
• Immunosuppression, HIV, chemotherapy, radiation, malnutrition, alcoholism
• Neonatal parotitis: prematurity, dehydration, low birth weight, ductal obstruction, oral trauma, structural abnormalities, immunosuppression
• JRP: dental malocclusion, congenital duct malformation, genetic factors, immunologic anomalies, disrupted enzyme activity
• Drug-induced parotitis: medications such as anticholinergics, ACE inhibitors (captopril), antihistamines, tricyclic antidepressants, antipsychotics (phenylbutazone, thioridazine, clozapine), iodine (contrast media), and L-asparaginase
• Chronic parotitis: ductal stenosis, HIV, tuberculosis, Sjögren syndrome, sarcoidosis, uremia, diabetes, gout, and atopy

General Prevention

• MMR vaccination
  • Pregnant women should not receive the mumps vaccine, and pregnancy should be avoided for 4 weeks after vaccination.
• Maintain adequate hydration and good dental hygiene; smoking cessation, abstinence from alcohol, and avoidance of chronic purging

Commonly Associated Conditions

Mumps, HIV, Sjögren syndrome, sarcoidosis, sialolithiasis