Sialolithiasis/salivary gland calculus

Etiology:

• Xerostomic meds
• Water hardness
• Hypercalcemia
• Tobacco smoking – cytotoxic effect on saliva, ↓ PMN phagocytic, ↓ salivary proteins
• Gout – only systemic disease known to cause salivary calculi and these are composed of uric acid

Submandibular duct:

• Inorganic deposits in the submandibular duct
• Initiated by a nidus (which is frequently of bacterial origin) – acts as a focus for dystrophic calcification
• The submandibular duct (wharton’s) is commonly affected due to:

1. Its tortuous course and longer duct – which encourages stasis within the duct
2. Higher mucous content in saliva
3. Saliva more alkaline
4. Higher concentration of calcium and phosphate in the saliva
5. Tendency of the saliva to flow against gravity – leaching of inorganic residues

• Ductal defects aggravate this condition – strictures and stenoses

Clinical:

• Unilateral, painful salivary gland swelling + intermittent symptoms that appear on salivation
• Acute ductal obstruction – may occur at meal time when saliva producing is at its maximum, the resultant swelling is sudden and can be painful (gustatory pain)
• Gradually reduction of the swelling can result but it recurs repeatedly when flow is stimulated.
• This process may continue until complete obstruction and/or infection occurs

Clinical history:

• History of swellings / change over time
• Trismus
• Pain
• Variation with meals
• Bilateral
• Dry mouth, dry eyes
• Recent exposure to sick contacts (mumps)
• Radiation history
• Current medications

Examination:

1. Inspection:

• Asymmetry (glands, face, neck)
• Diffuse or focal enlargement
• Erythema extra-orally
• Trismus
• Medial displacement of structures intraorally
• Examine external auditory canal (EAC)
• Cranial nerve testing

2. Palpation:

• Palpate for cervical lymphadenopathy
• Bimanual palpation of floor of mouth in a posterior to anterior direction
  o Have patient close mouth slightly & relax oral musculature to aid in detection
  o Examine for duct purulence
• Bimanual palpation of the gland (firm or spongy/elastic)

Histology:

• Prolonged obstruction – atrophy of the acini.
• A sialolith is distinguished by its calcific lamellar appearance

Radiology:

• Plain occlusal film
• Nearly 50% of calcifications are diffuse/ radiolucent so if the obstruction cannot be
  visualized on a plain xray, a sialogram should be done

NB:

• 80-90% of SMG calculi are radio-opaque
• 50-80% of parotid calculi are radiolucent

• 30% of SMG stones are multiple
• 60% of Parotid stones are multiple

Other diagnostic approaches:

1. CT Scan:
2. Ultrasound: Can detect small stones (>2mm), inexpensive, non-invasive
3. Sialography:
   • Opacification of the ducts – retrograde injection of a water-soluble dye.
   • Provides image of stones and duct morphological structure
   • Disadvantages:
     • i. Irradiation dose
     • ii. Pain with procedure
     • iii. Possibility of perforation
     • iv. Infection dye reaction
     • v. Push stone further
     • vi. Contraindicated in active infection
4. Radionuclide studies:
   • Useful to image the parenchyma
   • T99 – artificial radioactive element that – used as a tracer in imaging studies
   • Half life of 6 hours
   • Shares the Na-K-Cl transport system on the BM of the parotid acinar cells
5. MRI Sialography:
   • Advantage: No dye, no irradiation, no pain
   • Disadvantage: Cost, possible artifact
6. Diagnostic sialendoscopy:
   • Allows complete exploration of the ductal system, direct visualization of duct
     pathology
   • Success rate of >95%2
   • Disadvantage:
     • Technically challenging
     • Trauma could result in stenosis
     • Perforation

Management:

• Duct dilatation – to milk out the sialolith/ calcifications.
• None: antibiotics and anti-inflammatories
• Stone excision:
  • Lithotripsy
  • Interventional sialendoscopy
  • Simple removal (20% recurrence)
• Gland excision

If patients defer treatment, they need to know:
– Stones will enlarge over time
– Seek treatment early if infection develops
– Salivary gland massage and hyper-hydration when symptoms develop

Stone composition:

• Organic – often predominate in the center
• Glycoproteins
  • Mucopolysaccharides
  • Bacteria
  • Cellular debris
• Inorganic – often in the periphery
  • Calcium carbonates & calcium phosphates in the form of hydroxyapatite

Picture

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Mucoceles

Salivary gland cysts

Etiology: Pooling of saliva in tissues – secondary to trauma to a salivary gland

Classification: Pooling of saliva occurs:

• Within the gland – Retention cysts
  • Salivary duct blocked – expansion and formation of cysts
  • Epithelial lined
  • Adults
• Outside the gland – Extravasation cysts
  • Trauma – saliva spills into the tissues
  • Not epithelial lined
  • Kids
  • Neck cyst – extravasation cyst

Picture

NB:

• Cysts located on the floor of the mouth are called ranulas (Usually the
  extravasation type) Picture
• Ranulas can be superficial or unilateral
• Superficial ranulas: due to trauma to 1 or more excretory ducts of sublingual
  salivary gland
• If they burrow through the mylohyoid muscle (weak muscle), they are termed
  plunging ranulas. Picture
• The other common site is the lower lip.
• If the upper lip is involved, consider neoplasia

Common site: Lower lip > Floor of mouth > Palate > Buccal mucosa

Histology:

• Compressed fibrous CT
• Surrounding pooled, eosinophilic mucin
• Containing macrophages that have ingested mucin (mucinages)
• If retention cyst – epithelial lining and dilated duct
• If extravasation – no epithelial lining, remnants of ruptured salivary gland

Management: Surgical resection, excision, recurrences are common