Description

• Parotitis is caused by inflammation of the parotid gland due to infection, systemic illnesses, mechanical obstruction, or medications.
• The parotid gland is the largest salivary gland, located lateral and anterior to the masseter muscle, and extends posteriorly over the sternocleidomastoid muscle behind the angle of the mandible. It produces serous secretions, which lack bacteriostatic properties, making it more susceptible to infection than other salivary glands.
• The parotid duct, also called the Stensen duct, pierces the buccinator muscle and enters the buccal mucosa opposite the second maxillary molar.
• The branches of the facial nerve bisect the gland into lobes.

Epidemiology

• Viral parotitis is the most common cause of parotitis in children; incidence has decreased since the advent of the mumps vaccine.
• Acute bacterial parotitis is less common, but occurs more frequently in elderly patients, neonates, and postoperative patients.
• Juvenile recurrent parotitis (JRP): second most common inflammatory cause of parotitis in children in the United States; first episode usually occurs between ages 3 and 6 years.
• Chronic parotitis primarily affects adults; typically presents between ages 40 and 60 years
• Chronic bilateral parotid enlargement is a common manifestation of HIV infection.

Etiology and Pathophysiology

• Acute viral parotitis begins as a systemic infection that localizes to the parotid gland, resulting in inflammation and swelling.
  • Mumps, or paramyxovirus, has a predilection for the parotid gland and classically has been linked to parotitis 16 to 18 days after infection. Mumps is a nationally reportable disease.
  • Other viral pathogens: parainfluenza, enterovirus, echovirus, influenza A, coxsackievirus, Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6)
  • Cytomegalovirus (CMV) and adenovirus have been seen in patients with HIV.
  • Case reports demonstrate that parotitis can be a manifestation of SARS-CoV-2 infection.
• Acute bacterial parotitis results from stasis of salivary flow that allows retrograde introduction of bacterial pathogens into the gland, resulting in localized infection.
  • Staphylococcus aureus is most common, followed by Streptococcus pneumoniae and anaerobes. Less common are Streptococcus viridans, Escherichia coli, and Haemophilus influenzae.
  • Klebsiella, Enterobacter, and Pseudomonas can be seen in chronically ill or hospitalized patients.
  • Consider Bartonella henselae with cat exposure.
  • May be a manifestation of late-onset group B Streptococcus (rare)
  • Mycobacterium tuberculosis has been seen in immunocompromised patients.
• Fungal
  • Candida has been isolated in chronically ill or hospitalized patients.
  • Actinomyces in patients with a history of trauma or dental caries

• Acute, recurrent parotitis
  • Mechanical: Repeated sialolith formation leads to ductal wall damage, fibrosis, and stricture formation.
  • Pneumoparotitis occurs when air is trapped in the parotid gland ducts; seen in wind instrument players, glass blowers, scuba divers, and rarely with dental cleaning
• “Anesthesia mumps”: may be due to transient mechanical compression of the Stensen duct by airway devices, loss of muscle tone around the Stensen orifice after neuromuscular relaxants, increased salivary secretion, and increased flexion or rotation of the head during general anesthesia
• Chronic parotitis in patients with HIV can be due to presence of benign lymphoepithelial cysts, follicular hyperplasia of parotid lymph nodes, or diffuse infiltrative lymphocytosis syndrome, causing infiltration of the parotid gland by CD8 cells. Parotitis may be secondary to immune reconstitution after initiation of antiretroviral therapy.
• There are case reports of acute parotitis as a symptom of Kawasaki disease.

Risk Factors

• Immunosuppression, HIV, chemotherapy, radiation, malnutrition, alcoholism
• Acute viral parotitis: lack of mumps, measles, rubella (MMR) vaccination
• Acute bacterial parotitis: dehydration, debilitation, poor oral hygiene, Sjögren syndrome, cystic fibrosis, bulimia/anorexia, sialolithiasis (stones), ductal stenosis, trauma
• Neonatal parotitis: prematurity, dehydration, low birth weight, ductal obstruction, oral trauma, structural abnormalities
• JRP: dental malocclusion, congenital duct malformation, immunologic anomalies, disrupted enzyme activity
• Drug-induced parotitis: 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

• Completing MMR vaccine series; childhood vaccination does not guarantee prevention, possibly due to waning immunity with time.
  • Those without documented mumps immunity should receive 2 doses of the MMR vaccine, 28 days apart.
  • Pregnant women should not receive the mumps vaccine. Pregnancy should be avoided for 4 weeks after vaccination.
• Maintain adequate hydration, good dental hygiene, smoking cessation, abstinence from alcohol, and avoidance of chronic purging.

Commonly Associated Conditions

Mumps, HIV, Sjögren syndrome, sarcoidosis, sialolithiasis