Salivary Glands

💡Anatomy

💡Minor salivary glands

• Approximately 600–1,000 glands distributed throughout the oral mucosa.
• Common sites: lips, buccal mucosa, palate (especially posterior palate), tongue, floor of mouth and retromolar region.
• Generally absent from the anterior hard palate, attached gingiva and anterior dorsal tongue.
• Predominantly mucous secretion.
• The palate is the most common site for minor salivary gland tumours.

Rule of inverse proportion: The smaller the salivary gland, the greater the likelihood that a tumour is malignant.

💡Obstructive Disorders

Sialolithiasis (salivary stones)

Key facts

• Most common disease of the salivary glands.
• Approximately 80–90% of stones occur in the submandibular gland.
• Common composition: calcium phosphate and calcium carbonate, often with a hydroxyapatite core.

Why is the submandibular gland most commonly affected?

1. Wharton duct is long and tortuous.
2. Saliva travels against gravity.
3. Submandibular saliva is more viscous because of its mucous component.
4. Higher calcium and phosphate concentrations favour mineral deposition.

Clinical features

• Recurrent swelling and pain, particularly during meals.
• Palpable stone in the floor of the mouth.
• Secondary sialadenitis may develop.

Investigations

• Occlusal radiograph: Approximately 80% of submandibular stones are radiopaque.
• Parotid stones are more often radiolucent.
• Ultrasound and CT can help locate stones.
• Sialography is contraindicated in acute infection.

Management

Exam pearl: Meal-related pain and swelling are classic for obstructive salivary disease.

💡Mucocele

A mucocele is a mucus-containing lesion caused by salivary mucus escaping from a damaged duct or accumulating behind an obstructed duct.

The commonest form is the mucus extravasation phenomenon, which is not a true epithelial-lined cyst.

Types

Clinical features

• Dome-shaped, translucent or bluish swelling.
• Soft and fluctuant.
• Usually painless.
• Most common site: lower lip.
• Commonly associated with minor salivary glands.

Histology

In extravasation lesions, mucin is surrounded by granulation tissue and macrophages (muciphages), without an epithelial lining.

Treatment

• Surgical excision of the lesion, usually with the associated minor salivary gland.
• Incomplete removal of the involved gland can lead to recurrence.

💡Ranula

A ranula is a mucocele arising in the floor of the mouth, typically from the sublingual gland.

The name refers to its frog-belly appearance.

Simple oral ranula

• Confined to the floor of the mouth.
• Bluish, translucent, dome-shaped swelling.
• Soft and fluctuant.

Plunging ranula

• Extends through or around the mylohyoid muscle into the neck.
• May produce prominent cervical swelling with minimal intraoral findings.

Treatment

• Simple ranula: marsupialization or excision in selected cases.
• Plunging ranula: removal of the sublingual gland with management of the cervical component as required.

Definitive treatment pearl: Removing the sublingual gland addresses the source and reduces recurrence. Drainage or marsupialization alone has a higher recurrence risk.

💡Inflammatory Disorders

💡Acute sialadenitis (acute suppurative parotitis)

Most common organism: Staphylococcus aureus, typically ascending through the salivary duct.

Predisposing factors

• Dehydration.
• Postoperative state.
• Xerostomia.
• Debilitated patients.
• Sialolithiasis or duct obstruction.

Clinical features

• Sudden, painful gland swelling.
• Tenderness, warmth and overlying erythema.
• Purulent discharge from the duct orifice when the gland is massaged.
• Fever and malaise.
• Parotid infection may produce swelling near the ear and angle of the mandible.

Treatment

• Hydration.
• Appropriate anti-staphylococcal antibiotics, such as flucloxacillin where suitable.
• Warm compresses and gentle gland massage.
• Sialogogues.
• Incision and drainage if an abscess develops.

💡Chronic sialadenitis

Causes

• Recurrent acute infections.
• Salivary stones and duct strictures.
• Previous radiation exposure.

Clinical features

• Recurrent episodes of gland swelling and pain.
• Progressive fibrosis and loss of gland function.
• The gland may become firm.

Chronic sclerosing sialadenitis (Küttner tumour)

• Usually affects the submandibular gland.
• Associated with IgG4-related disease.
• Produces a firm mass that may clinically resemble a tumour.

Management: Conservative treatment for mild disease; sialadenectomy may be required for severe or recurrent disease.

💡Mumps (epidemic parotitis)

Etiology: Mumps virus, a paramyxovirus, spread through respiratory droplets and saliva.

Incubation period: Approximately 14–21 days.

Clinical features

• Bilateral parotid swelling in approximately 70% of cases.
• Tender gland enlargement.
• Fever and malaise.
• Upward and outward displacement of the ear lobe is a classic examination finding.

Complications

Diagnosis and prevention

• Diagnosis is based on the clinical picture and may be supported by mumps-specific IgM or molecular testing.
• Prevention: MMR vaccination.
• Treatment: Supportive care; the infection is generally self-limiting.

💡Autoimmune Disease — Sjögren Syndrome

Definition: A chronic autoimmune disorder involving destruction or dysfunction of exocrine glands, particularly salivary and lacrimal glands.

Types

Key clinical features

Oral manifestations

• Xerostomia.
• Bilateral parotid enlargement in approximately 30% of patients.
• Increased dental caries, particularly cervical caries.
• Oral candidiasis.
• Dysphagia due to reduced lubrication.
• Dry, fissured or depapillated tongue.

Ocular manifestations

• Keratoconjunctivitis sicca.
• Burning, gritty sensation and dry eyes.

Investigations

• Anti-Ro/SSA: Important diagnostic antibody.
• Anti-La/SSB: Additional associated antibody.
• Schirmer test: Reduced tear production; a result of less than 5 mm wetting in 5 minutes supports ocular dryness.
• Minor salivary gland biopsy: Focal lymphocytic sialadenitis; a focus score of at least 1 focus per 4 mm² supports the diagnosis.

Major long-term risk

Sjögren syndrome is associated with a substantially increased risk of B-cell non-Hodgkin lymphoma, particularly MALT lymphoma. The notes highlight an approximately 44-fold increase in NHL risk.

Persistent or asymmetric gland enlargement, lymphadenopathy and focal gland lesions warrant further assessment.

Management

• Artificial tears.
• Saliva substitutes.
• Pilocarpine, a muscarinic agonist, when appropriate.
• Intensive fluoride prevention and regular dental review.
• Hydroxychloroquine may be used for selected systemic manifestations.

FCPS pearl: Dry mouth + dry eyes + anti-Ro/SSA positivity + focal lymphocytic sialadenitis strongly suggests Sjögren syndrome.

💡Salivary Gland Tumours

General principles

The parotid gland accounts for the majority of salivary gland tumours, but tumours arising in smaller glands have a higher likelihood of malignancy.

💡Pleomorphic adenoma (benign mixed tumour)

Most common salivary gland tumour overall.

• Accounts for approximately 60–65% of salivary gland tumours.
• Most common site: superficial lobe of the parotid.
• Usually affects adults aged 30–60 years, with a slight female predominance.

Clinical features

• Slow-growing.
• Painless, firm, mobile mass.
• Well-circumscribed clinically.

Histology

A mixture of:

• Epithelial cells.
• Myoepithelial cells.
• Myxoid and chondroid stroma.

This combination gives rise to the term mixed tumour.

Treatment

• Superficial parotidectomy for appropriate superficial-lobe lesions, preserving the facial nerve.
• Enucleation alone is avoided because of the risk of recurrence.

Why does it recur after enucleation?

The tumour may have an incomplete capsule, with pseudopod-like extensions extending beyond the apparent boundary. Simple enucleation can leave residual tumour tissue.

Malignant transformation: Carcinoma ex pleomorphic adenoma becomes a concern with long-standing tumours; the risk increases with duration, particularly after 15 years.

💡Warthin tumour

Also called papillary cystadenoma lymphomatosum.

• Second most common benign salivary gland tumour.
• Occurs almost exclusively in the parotid, particularly its tail.
• Strong association with smoking.
• Usually affects older men.

Clinical features

• Soft, cystic or fluctuant, painless mass below or in front of the ear.
• May be bilateral in approximately 10% of cases.
• May be multifocal in approximately 10% of cases.

Histology

• Papillary cystic spaces.
• Oncocytic epithelium with eosinophilic granular cytoplasm.
• Dense lymphoid stroma containing germinal centres.

Investigation

Technetium-99m pertechnetate scan: Warthin tumours may demonstrate increased uptake, producing a “hot” scan.

Treatment

• Observation in selected cases or surgical excision, depending on diagnosis, symptoms and patient factors.
• No significant malignant potential in the classic tumour.

💡Pleomorphic adenoma vs Warthin tumour

💡Mucoepidermoid carcinoma

Most common malignant salivary gland tumour overall, including in children.

Cell types

• Mucous cells.
• Epidermoid (squamoid) cells.
• Intermediate cells.

Grading

Clinical features

• Painless gland mass is common in low-grade lesions.
• High-grade tumours may be painful, fixed or associated with nerve dysfunction.
• Commonly affects the parotid and minor salivary glands.

Treatment

• Surgical excision.
• Radiotherapy may be used for high-grade disease or other adverse pathological features.

Exam pearl: Mucoepidermoid carcinoma is the most common malignant salivary gland tumour and an important salivary malignancy in children.

💡Adenoid cystic carcinoma

Second most common malignant salivary gland tumour in the notes.

• Commonly affects the submandibular gland and palatal minor salivary glands.
• Characteristically demonstrates perineural invasion.
• May cause pain, numbness or facial nerve palsy despite a relatively small tumour.

Histological patterns

1. Cribriform pattern

• Most common pattern.
• Multiple rounded spaces containing hyaline material.
• Classic “Swiss cheese” appearance.

2. Tubular pattern

• Generally associated with the best prognosis.

3. Solid pattern

• Associated with the worst prognosis.

Clinical behaviour

• Slow-growing but locally aggressive.
• Perineural invasion is the hallmark.
• Haematogenous metastasis commonly involves the lungs.
• Distant metastases may appear 10–20 years after initial treatment.
• Late recurrence makes long-term follow-up essential.

Treatment

• Wide surgical excision.
• Postoperative radiotherapy is commonly used.

Exam pearl: Adenoid cystic carcinoma = perineural invasion + cribriform “Swiss cheese” histology + late lung metastasis.

💡Acinic cell carcinoma

• Arises from serous acinar cells.
• Occurs almost exclusively in the parotid gland.
• Usually low-grade, with a favourable prognosis.
• Rarely bilateral.

Treatment: Surgical excision; prognosis is generally excellent in low-grade disease.

💡High-Yield Comparison Tables

Benign salivary gland tumours

Malignant salivary gland tumours