5.3 Salivary Gland Disorders, Sialadenitis & Cysts of the Jaws

5.3 Salivary Gland Disorders, Sialadenitis & Cysts of the Jaws

Salivary gland diseases and cysts of the jaws represent major diagnostic entities in oral medicine and pathology. Candidates must master clinical diagnostic differentiation, radiographic presentation, histopathological signatures, and surgical principles.

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1. Non-Neoplastic Salivary Gland Lesions

A. Mucoceles & Ranulas

• Mucous Extravasation Phenomenon (Extravasation Mucocele): Represents 90% of mucoceles. Caused by mechanical trauma (e.g., lip biting) severing a minor salivary gland duct, leaking mucin into surrounding connective tissue. Characteristically lacks an epithelial lining (it is a pseudocyst surrounded by granulation tissue and foamy histiocytes/macrophages). Occurs most frequently on the lower labial mucosa.
• Mucous Retention Cyst: True cyst lined by ductal epithelium caused by ductal obstruction (sialolith, mucus plug). Commonly found in older adults on upper lip or palate.
• Ranula: A mucocele located on the floor of the mouth arising from the sublingual salivary gland.
  • Superficial Ranula: Bluish, translucent swelling above the mylohyoid muscle.
  • Plunging Ranula: Mucin dissects inferiorly through the mylohyoid muscle, presenting as a soft tissue swelling in the submandibular or neck region.

B. Sialolithiasis & Sialadenitis

• Sialolithiasis (Salivary Calculi): Formation of calcified concretions within salivary ductal systems.
  • Submandibular Gland (Wharton's Duct): Accounts for 80–90% of sialoliths. Reasons for submandibular predominance include:
    1. Higher mucin content and viscosity of submandibular saliva.
    2. Higher concentration of calcium and phosphate ions.
    3. Upward, tortuous, long course of Wharton's duct.
    4. Dependent position of the gland.
  • Clinical Symptoms: Classic "salivary colic" — acute, painful swelling of the gland during or immediately following meals (stimulated saliva production blocked by stone).
  • Sialadenitis: Acute bacterial sialadenitis (Staphylococcus aureus) presenting with purulent discharge from duct orifices in dehydrated patients; Viral sialadenitis (Mumps / Paramyxovirus); Autoimmune sialadenitis (Sjögren Syndrome).

C. Sjögren Syndrome

An autoimmune exocrinopathy destroying salivary and lacrimal glands.

• Primary Sjögren Syndrome: Sicca complex (Xerostomia + Keratoconjunctivitis sicca).
• Secondary Sjögren Syndrome: Sicca complex + co-existing connective tissue disease (Rheumatoid Arthritis, Systemic Lupus Erythematosus).
• Serology & Diagnosis: Positive anti-SSA (Ro) and anti-SSB (La) autoantibodies. Labial salivary gland biopsy demonstrating focal lymphocytic sialadenitis with a focus score ≥1 (cluster of ≥50 lymphocytes per 4 mm² tissue).
• Malignancy Risk: Patients with Sjögren syndrome have a 44-fold increased risk of developing Non-Hodgkin MALT Lymphoma.

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2. Salivary Gland Neoplasms

A vital rule for the ADC examination is the "Rule of Salivary Gland Tumor Proportions":

• Parotid Gland: ~80% of all salivary tumors; ~80% are benign.
• Submandibular Gland: ~50% are benign; ~50% are malignant.
• Sublingual & Minor Salivary Glands: ~80% are malignant.

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3. Cysts of the Jaws

Cysts of the oral and maxillofacial region are fluid-filled pathological cavities lined by epithelium.

                            Jaw Cysts Classification
                                      │
              ┌───────────────────────┴───────────────────────┐
              ▼                                               ▼
     Odontogenic Cysts                               Non-Odontogenic Cysts
  ┌───────────┴───────────┐                         ┌─────────┴─────────┐
  ▼                       ▼                         ▼                   ▼
Inflammatory         Developmental             Nasopalatine        Globulomaxillary
(Radicular Cyst)  (Dentigerous, OKC)            Duct Cyst           (Anatomical)

A. Inflammatory Odontogenic Cysts

• Radicular Cyst (Periapical Cyst): The most common jaw cyst (60–70%). Initiated by pulpal necrosis following dental caries or trauma. Bacteria stimulate proliferation of the Rests of Malassez within the periodontal ligament. Lined by non-keratinized stratified squamous epithelium. Associated with a non-vital tooth.

B. Developmental Odontogenic Cysts & Tumors

• Dentigerous Cyst (Follicular Cyst): Encloses the crown of an unerupted or impacted tooth (most commonly mandibular third molars and maxillary canines) and attaches to the tooth at the cementoenamel junction (CEJ). Originates from fluid accumulation between the reduced enamel epithelium and the enamel surface. Radiographically appears as a well-defined unilocular radiolucency surrounding the crown.
• Odontogenic Keratocyst (OKC): Derived from the dental lamina. Highly aggressive with a high recurrence rate (up to 30%). Radiographically presents as a well-demarcated unilocular or multilocular radiolucency expanding anteroposteriorly in the posterior body/ramus of the mandible without marked cortical expansion.
  • Histopathology: Uniform 6–8 cell layer thickness of parakeratinized epithelium, prominent palisaded basal cell layer with hyperchromatic "tombstone" nuclei, corrugated parakeratin surface, and absence of rete ridges.
  • Syndrome Association: Multiple OKCs are a key component of Nevoid Basal Cell Carcinoma Syndrome (Gorlin-Goltz Syndrome), caused by mutations in the PTCH1 gene.
• Ameloblastoma: Benign, locally destructive, aggressive odontogenic neoplasm. Most common in posterior mandible. Radiographically shows a classic "soap bubble" or "honeycomb" multilocular radiolucency with cortical expansion and root resorption.
  • Histopathology: Islands of odontogenic epithelium with outer columnar cells exhibiting reverse nuclear polarity (nuclei aligned away from the basement membrane) and an inner core resembling the stellate reticulum. Requires radical surgical resection with 1 cm clear bony margins due to high recurrence following curettage.

C. Non-Odontogenic Cysts

• Nasopalatine Duct Cyst (Incisive Canal Cyst): Arises from epithelial remnants of the nasopalatine duct within the incisive canal. Radiographically presents as a well-defined heart-shaped radiolucency located between the roots of the maxillary central incisors. Teeth involved remain vital.