Description

• Parotitis is inflammation of the parotid gland caused by infection (viral or bacterial), noninfectious systemic illnesses, mechanical obstruction, or medications.
• 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 Stensen's duct, pierces the buccinator muscle to enter the buccal mucosa just opposite the second maxillary molar.
• The branches of the 7th cranial nerve divide the gland into lobes.
• The parotid gland contains lymph nodes.
• Parotitis can be unilateral or bilateral, acute or chronic.

Epidemiology

• Prior to widespread vaccination, parotitis was primarily caused by mumps virus; once 150,000 cases per year, now, 1,600 cases per year occur due to occasional sporadic outbreaks.
• Acute bacterial parotitis occurs more frequently in elderly patients, neonates (especially preterm infants), and postoperative patients.
• Neonatal parotitis is more common in males than females.
• 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.
• Juvenile recurrent parotitis is the most common inflammatory salivary gland disorder in the US; first onset of symptoms occurs between the ages of 3 and 6.

Risk Factors

• Acute viral parotitis: Lack of mumps, measles, rubella (MMR) vaccination
• Acute bacterial parotitis:
  • Conditions that predispose to salivary stasis, such as dehydration, debilitation, poor oral hygiene, Sjögren syndrome, cystic fibrosis, bulimia/anorexia, sialolithiasis (stones), ductal stenosis, trauma
  • Medications such as anticholinergics, antihistamines, diuretics, tricyclic antidepressants, thioridazine, iodine
  • Immunosuppression, HIV, chemotherapy, radiation, malnutrition, alcoholism
• Neonatal parotitis: Prematurity, low birth weight, ductal obstruction, oral trauma, structural abnormalities, immunosuppression
• Chronic parotitis:
  • Ductal stenosis, HIV, tuberculosis, Sjögren syndrome, sarcoidosis

General Prevention

• MMR vaccination with the 1st dose between 12 and 15 months and 2nd dose between 4 and 6 years of age; of note, mumps vaccination does not guarantee prevention, possibly due to waning immunity in adolescence
• Maintain adequate hydration and good dental hygiene.
• Sucking on hard or sour candies can stimulate salivary flow and prevent salivary stasis.
• Smoking cessation, abstinence from alcohol, and avoidance of chronic purging

Pathophysiology

• Acute viral parotitis begins as a systemic infection that localizes to the parotid gland, resulting in inflammation and swelling of the gland:
  • Mumps, or paramyxovirus, has a predilection for the parotid gland and classically has been linked with parotitis.
• For bacterial parotitis, stasis of salivary flow allows retrograde introduction of bacterial pathogens into parotid gland, resulting in localized infection.
• Chronic parotitis in HIV-infected patients can be due to the presence of benign lymphoepithelial cysts, follicular hyperplasia of parotid lymph nodes, or diffuse infiltrative lymphocytosis syndrome (DILS) causing infiltration of the parotid gland by CD8 cells:
  • Parotitis may also be secondary to immune reconstitution after initiation of combination antiretroviral therapy in HIV-infected patients.

Etiology

• Acute parotitis due to infection:
  • Viral:
    • Paramyxovirus (mumps), parainfluenza virus types 1 and 3, influenza A, coxsackie viruses, Epstein-Barr virus (EBV)
    • Cytomegalovirus (CMV) and adenovirus have been seen in patients with HIV.
  • Bacterial:
    • Staphylococcus aureus and anaerobes (oral flora) are most commonly seen.
    • Streptococcus pneumoniae, Escherichia coli, and Haemophilus influenza (less common)
    • Gram-negative rods such as E. coli, Klebsiella, Enterobacter, and Pseudomonas can be seen in chronically ill or hospitalized patients.
  • Fungal:
    • Candida has been isolated in chronically ill or hospitalized patients.
    • Actinomyces can be found in patients with a history of trauma or dental caries.
• Acute, recurrent parotitis:
  • Juvenile recurrent parotitis may be secondary to chronic inflammation; etiology is unknown, but a genetic component has been described.
  • Mechanical: Sialolithiasis, ductal stenosis
  • Pneumoparotitis may occur when air is trapped in the ducts of the parotid gland; may be seen in wind instrument players, glass blowers, and scuba divers
  • Medications: Anticholinergics, antihistamines, tricyclic antidepressants, thioridazine, iodine
  • Other: Diabetes, alcoholism, bulimia, “anesthesia mumps” (due to transient mechanical compression of Stensen's duct by airway devices and increased salivary secretion during general anesthesia)
• Chronic parotitis:
  • HIV
  • Tuberculosis, syphilis (rare)
  • Autoimmune: Sjögren syndrome (parotid enlargement, xerostomia, and keratoconjunctivitis)
  • Inflammatory: Sarcoidosis:
    • Heerfordt syndrome (parotid enlargement, facial palsy, and uveitis) is a rare manifestation of sarcoidosis

Commonly Associated Conditions

HIV, Sjögren syndrome, sarcoidosis, sialolithiasis