11.4 Salivary Gland Disease

Mucocele and Ranula

• Mucocele is the most common salivary gland lesion. Two types:
  • Mucous extravasation 'cyst' (most common) — saliva pools in connective tissue after trauma to a minor gland duct; no epithelial lining. Classical site: lower lip. Patients: children/young adults; bluish translucent fluctuant swelling that fluctuates in size; not acutely tender.
  • Mucous retention cyst — true epithelial-lined cavity, less common, often older patients.
• Management: excision of the cyst and the associated minor gland (recurrence occurs if the feeding gland is left).
• Ranula — a mucocele in the floor of mouth above the mylohyoid; appears as a bluish cross-shaped swelling. Plunging ranula herniates through the mylohyoid to present as a neck swelling crossing the submental and submandibular regions. Management: marsupialisation, excision of the sublingual gland, or sclerotherapy for plunging ranula.

Acute Bacterial Sialadenitis

• Most often affects the parotid and submandibular glands.
• Risk factors: dehydration, reduced flow (post-operative, elderly, radiotherapy), medications with anticholinergic effect, Sjögren's.
• Ascending ductal infection: Staphylococcus aureus, Streptococcus viridans, occasionally anaerobes.
• Presentation: painful, swollen, tender gland; pus from the duct orifice on massage; fever; malaise.
• Management: hydration, warm massage, sialogogues, antibiotics (flucloxacillin first-line; clindamycin if penicillin-allergic). Most settle within days; gland abscess requires surgical drainage.

Sialolithiasis

• Formation of a salivary stone (calculus).
• Around 80% occur in the submandibular gland (Wharton's duct), ~20% in the parotid (Stensen's duct).
• Why the submandibular gland? mucinous alkaline saliva, longer duct, anti-gravity flow, higher calcium and phosphate content.
• Presentation: painful swelling at mealtimes that resolves between meals; can become chronic/recurrent.
• Radio-opacity: around 80% of submandibular stones are radio-opaque (vs ~40–60% of parotid stones) on plain film.
• Imaging: occlusal radiograph for anterior submandibular stones; CBCT; ultrasound; sialography is largely superseded by sialoendoscopy.
• Management:
  • Distal stones — removal via the duct orifice (bimanual massage, intraoral incision).
  • Proximal / intraglandular stones — interventional sialoendoscopy first-line where available; gland excision if recurrent or refractory.

Salivary Gland Tumours

Pleomorphic Adenoma

• Most common salivary gland tumour (~60% of all salivary neoplasms).
• ~80% arise in the parotid (usually superficial lobe); also submandibular and minor glands (palate).
• Histology: myoepithelial cells + stromal elements (chondroid, myxoid) — 'mixed tumour'.
• Well-encapsulated; recurs if ruptured/spilled — strict superficial parotidectomy with facial nerve preservation is the management, not enucleation.
• Small risk of malignant transformation (carcinoma ex-pleomorphic adenoma) — sudden rapid growth, pain, or facial nerve palsy in a long-standing parotid mass is a red flag.

Warthin's Tumour

• 2nd most common benign parotid tumour.
• Parotid tail; smokers; male predominance; bilateral in ~5–10% of cases.
• Cystic spaces with papillary projections and a lymphoid stroma.
• Management: superficial parotidectomy; benign. May be observed if small and asymptomatic in selected patients.

Mucoepidermoid Carcinoma

• Most common salivary malignancy in both adults and children.
• Parotid is the most common site.
• Mucous, epidermoid, and intermediate cells; grading (low/intermediate/high) drives prognosis.
• TNM staging; surgery ± radiotherapy.

Adenoid Cystic Carcinoma

• Cribriform 'swiss cheese' pattern (most characteristic); also tubular and solid (worst prognosis).
• Perineural invasion is the hallmark — skip lesions along nerves; facial nerve involvement common in parotid tumours, causing pain or weakness.
• Slow indolent course but late local recurrence and distant metastases (lung > bone); long-term prognosis is poor despite indolence.
• Surgery + radiotherapy; not chemotherapy responsive.

Sjögren's Syndrome

• Primary Sjögren's: xerostomia + keratoconjunctivitis sicca without another connective tissue disease. Autoimmune lymphocytic destruction of exocrine glands. Strongly associated with anti-Ro/SSA and anti-La/SSB antibodies (anti-La/SSB more specific).
• Secondary Sjögren's: with rheumatoid arthritis, SLE, or other connective tissue disease.
• Investigations: Schirmer's test (<5 mm in 5 min), unstimulated whole saliva flow, serology (anti-Ro/SSA, anti-La/SSB, ANA, rheumatoid factor), and minor salivary gland biopsy (focus score ≥1 per 4 mm²).
• Increased risk of lymphoma — overall lifetime risk around 5–10%, with a markedly increased relative risk (~16–44×) of B-cell lymphoma, most often MALT lymphoma. Watch for persistent unilateral parotid enlargement, new firmness or nodularity, or rising immunoglobulin levels — investigate with imaging and biopsy.

Xerostomia and Sialorrhoea

Xerostomia (dry mouth) — causes and management:

Sialorrhoea (excess saliva) — cerebral palsy, Parkinson's disease, developmental disorders, teething, pregnancy. Management: anticholinergics (hyoscine), botulinum toxin injection into the major salivary glands, or surgical duct repositioning in selected cases.

MFDS red flag: A parotid mass with new facial nerve weakness is not a benign pleomorphic adenoma until proven otherwise — the differential includes adenoid cystic carcinoma, carcinoma ex-pleomorphic adenoma, and primary salivary malignancy. Refer urgently to a head and neck MDT.