Sialadenitis Pathophysiology, Diagnosis, and Management

Introduction

Sialadenitis is an inflammatory disorder of the salivary glands, most commonly affecting the parotid and submandibular glands. The condition can arise from infectious, autoimmune, or obstructive etiologies and presents with glandular swelling, pain, and, in acute cases, systemic features such as fever. While acute bacterial sialadenitis is a relatively straightforward diagnosis, chronic and recurrent forms may mimic other pathologies, including salivary gland neoplasms. The diagnosis and management of sialadenitis require careful clinical evaluation, imaging, microbiological analysis, and in some cases, surgical intervention.

Anatomy and Physiology of Salivary Glands

Humans possess three major salivary glands—the parotid, submandibular, and sublingual—along with numerous minor salivary glands scattered throughout the oral cavity. These glands produce saliva, which plays an essential role in digestion, lubrication, oral mucosa protection, antimicrobial defense, and maintenance of dental health. Obstruction or infection in these glands disrupts normal salivary flow, predisposing the tissue to inflammation and infection.

Etiology

Sialadenitis can be classified based on cause:

1. Infectious Causes
   • Bacterial: Most commonly Staphylococcus aureus, followed by Streptococcus viridans, Haemophilus influenzae, and anaerobes.
   • Viral: Mumps virus (epidemic parotitis), HIV, and cytomegalovirus.
2. Obstructive Causes
   • Sialolithiasis (salivary stones), most often in the submandibular gland due to its tortuous duct and alkaline saliva.
   • Strictures of salivary ducts.
3. Autoimmune Causes
   • Sjögren’s syndrome leading to chronic sialadenitis.
   • Sarcoidosis and IgG4-related disease.
4. Other Factors 
   • Dehydration, poor oral hygiene, immunosuppression, and medications reducing salivary flow (anticholinergics, diuretics, antihistamines).

Pathophysiology

Obstruction of salivary flow, whether due to sialolithiasis or ductal stricture, creates a favorable environment for bacterial colonization. Stasis of saliva impairs natural antimicrobial activity and allows retrograde infection from the oral cavity. In autoimmune diseases, lymphocytic infiltration damages acinar tissue, leading to fibrosis and chronic gland dysfunction. Viral causes, particularly mumps, directly infect glandular epithelial cells, resulting in parenchymal inflammation and edema.

Clinical Presentation

Acute Sialadenitis

• Sudden painful swelling of the gland, often unilateral.
• Tenderness, erythema, and warmth overlying skin.
• Purulent discharge from the duct orifice on massage.
• Fever, malaise, and systemic symptoms in severe cases.

Chronic Sialadenitis

• Recurrent episodes of swelling, usually associated with meals.
• Firm gland, intermittent pain, and sometimes xerostomia.
• May mimic tumor-like enlargement.

Viral Sialadenitis (Mumps)

• Bilateral parotid swelling.
• Fever, malaise, and myalgia.
• Self-limiting but may lead to complications such as orchitis, pancreatitis, and meningitis.

Autoimmune Sialadenitis

• Persistent dry mouth and eyes (Sjögren’s syndrome).
• Recurrent swelling and gradual destruction of glandular tissue.

Diagnostic Evaluation

1. History and Physical Examination
   • Onset, duration, recurrence, associated systemic symptoms.
   • Palpation of gland, assessment of ductal discharge, and evaluation for stones. 
2. Laboratory Tests 
   • Complete blood count and inflammatory markers.
   • Microbiological culture of pus or discharge.
   • Autoimmune markers (anti-SSA/Ro, anti-SSB/La antibodies) for Sjögren’s syndrome.
3. Imaging
   
   • Ultrasound: First-line modality, detecting abscesses, stones, and ductal dilation.
   • Sialography: Evaluates ductal anatomy and obstruction.
   • CT/MRI: Useful for deep gland involvement, abscess, or differentiation from tumors.
   • Sialendoscopy: Both diagnostic and therapeutic, allowing visualization of ductal system.
4. Biopsy
   • Indicated when autoimmune disease or neoplasm is suspected.

Management

Acute Bacterial Sialadenitis

• Hydration and salivary stimulation: Sialogogues (lemon drops), gland massage, and warm compresses.
• Antibiotics: Empirical coverage against S. aureus and oral flora, such as dicloxacillin, cephalosporins, or clindamycin. Severe cases may require IV antibiotics.
• Analgesics and anti-inflammatory drugs.
• Drainage of abscesses if present.

Viral Sialadenitis

• Supportive management: rest, hydration, analgesia.
• Isolation in mumps to prevent transmission.
• Vaccination (MMR) as prevention.

Chronic and Obstructive Sialadenitis

• Sialolithiasis management:
  • Small stones: massage, sialogogues, hydration.
  • Larger stones: sialendoscopy, lithotripsy, or surgical removal.
• Chronic inflammation: May require gland excision if recurrent and refractory.

Autoimmune Sialadenitis

• Symptomatic treatment for xerostomia (artificial saliva, pilocarpine).
• Immunosuppressive therapy for systemic Sjögren’s or IgG4-related disease.

Complications

• Abscess formation
• Spread to deep neck spaces (life-threatening)
• Fistula formation
• Recurrent chronic infection leading to gland fibrosis
• Secondary malignancy risk in longstanding Sjögren’s syndrome (e.g., lymphoma)

Prognosis

Most cases of acute bacterial sialadenitis resolve with prompt antibiotic therapy and supportive care. Chronic and autoimmune cases may be more challenging, requiring long-term management and sometimes surgery. With early recognition, serious complications can be prevented.

Public Health and Preventive Aspects

• Adequate hydration and good oral hygiene reduce risk.
• Avoidance of unnecessary medications that cause dry mouth.
• Widespread MMR vaccination has significantly reduced viral sialadenitis due to mumps.
• Awareness programs regarding Sjögren’s syndrome and autoimmune disorders are important for early detection.

Conclusion

Sialadenitis is a multifactorial condition with diverse etiologies ranging from infections to autoimmune disorders. While most acute bacterial cases respond well to conservative measures and antibiotics, chronic and autoimmune forms require more complex diagnostic and therapeutic approaches. Advances in sialendoscopy and minimally invasive procedures have revolutionized the management of obstructive sialadenitis, reducing the need for major surgery. Continued research and awareness are crucial for improving patient outcomes and preventing recurrence.

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