19.4 Salivary Gland Diseases: Obstruction, Infection, Sjögren Syndrome and Tumors
Key Takeaways
About 80% or more of salivary stones form in the submandibular gland because its duct is long, runs uphill and carries more viscous, alkaline saliva; they cause swelling and pain at mealtimes.
The smaller the salivary gland, the more likely a tumor in it is malignant: most parotid tumors are benign, whereas most sublingual gland tumors are malignant.
Pleomorphic adenoma is the most common salivary tumor and recurs if simply enucleated because of its incomplete capsule, while mucoepidermoid carcinoma is the most common malignant salivary tumor.
Adenoid cystic carcinoma spreads along nerves (perineural invasion), causing pain or numbness, and can metastasize late to the lungs.
Sjögren syndrome causes dry mouth and dry eyes with anti-Ro (SSA) and anti-La (SSB) antibodies, is confirmed by labial minor salivary gland biopsy, and raises the risk of MALT lymphoma.
Salivary questions are usually recognition tasks: a lower lip swelling, a swelling at mealtimes, a dry mouth, or a parotid lump. Know the most common lesion in each site and the sign that suggests malignancy.
Mucous Lesions
| Lesion | Features | Management |
|---|---|---|
| Mucocele (mucus extravasation) | Bluish, fluctuant swelling, most often on the lower lip, after trauma to a minor gland duct; may rupture and recur | Excision with the associated minor glands to prevent recurrence |
| Ranula | Large mucocele of the sublingual gland in the floor of mouth ("frog belly"); a plunging ranula passes through the mylohyoid into the neck | Excision of the sublingual gland (marsupialization alone often recurs) |
| Mucus retention cyst | True epithelium-lined cyst, older adults | Excision |
Sialolithiasis
- About 80% or more of stones form in the submandibular gland: the duct is long and runs uphill against gravity, and the saliva is more mucinous and alkaline with more calcium.
- Symptoms: pain and swelling at mealtimes ("mealtime syndrome") that settle afterwards; recurrent infection.
- Imaging: mandibular occlusal radiograph for submandibular duct stones (not all stones are radiopaque), ultrasound, CT or sialography (not during acute infection).
- Treatment: sialogogues, massage and hydration for small stones; removal through the duct for anterior stones (place a suture behind the stone to stop it slipping back); sialendoscopy; gland excision for stones within the gland or recurrent disease.
Infection and Inflammation
| Condition | Features |
|---|---|
| Acute bacterial sialadenitis | Usually the parotid in dehydrated, elderly or post-operative patients; painful swelling with pus from Stensen's duct; Staphylococcus aureus; treat with hydration, sialogogues, antibiotics, drainage |
| Mumps | Viral, usually bilateral painful parotid swelling in children; vaccine-preventable |
| Chronic sialadenitis | Repeated obstruction or infection, gland fibrosis |
| Necrotizing sialometaplasia | Deep ulcer of the hard palate after ischemia (for example after injection or surgery); mimics carcinoma clinically and histologically; heals spontaneously within several weeks once biopsy has confirmed it |
| Sialosis (sialadenosis) | Painless bilateral parotid enlargement in diabetes, alcoholism, bulimia and malnutrition |
Xerostomia and Sjögren Syndrome
Xerostomia is the symptom of dry mouth; hyposalivation is a measured reduction (unstimulated whole saliva below about 0.1 mL/min). Causes: medications (the most common cause: antidepressants, antihistamines, antihypertensives, anticholinergics), head and neck radiotherapy, Sjögren syndrome, dehydration, diabetes, and aging combined with medications.
Consequences: cervical and root caries, candidiasis, difficulty with dentures, speech and swallowing, altered taste.
Management: treat the cause and review medications; sugar-free gum or lozenges; saliva substitutes; frequent water; high-fluoride toothpaste or varnish and diet control; pilocarpine (about 5 mg three times daily) or cevimeline when residual gland function exists; avoid these sialogogues in uncontrolled asthma and narrow-angle glaucoma.
Sjögren syndrome
- An autoimmune exocrinopathy, mostly in middle-aged women; primary (dry eyes and mouth only) or secondary (with rheumatoid arthritis, SLE or another connective tissue disease).
- Tests: anti-Ro (SSA) and anti-La (SSB) antibodies, Schirmer test for tear flow, salivary flow rate, and labial minor salivary gland biopsy showing focal lymphocytic sialadenitis (focus score of at least 1).
- Recurrent parotid enlargement; increased risk of MALT (marginal zone B-cell) lymphoma, so a persistent firm parotid enlargement needs investigation.
Salivary Gland Tumors
| Gland | Share of tumors (approximate) | Proportion malignant |
|---|---|---|
| Parotid | Most salivary tumors | Minority (about 20-25%) |
| Submandibular | Smaller share | About 40-50% |
| Sublingual | Rare | Majority |
| Minor glands (palate most common) | Moderate share | About half or more |
Rule of thumb: the smaller the gland, the higher the chance of malignancy.
| Tumor | Key points |
|---|---|
| Pleomorphic adenoma | Most common salivary tumor; painless slowly growing mass, usually parotid (superficial lobe) or palate (lateral posterior hard palate); incomplete capsule with extensions, so enucleation leads to recurrence; treat by superficial parotidectomy or excision with margins; small risk of malignant change after many years |
| Warthin tumor | Second most common parotid tumor; tail of parotid, older men, strongly linked to smoking; can be bilateral; almost exclusively in the parotid |
| Mucoepidermoid carcinoma | Most common malignant salivary tumor (also most common in children); parotid or palate; may be bluish and mimic a mucocele; graded low to high |
| Adenoid cystic carcinoma | Minor glands (palate) and submandibular gland; perineural invasion causing pain, numbness or facial palsy; slow but relentless with late lung metastases |
| Polymorphous adenocarcinoma | Almost exclusively minor glands, especially the palate |
| Acinic cell carcinoma | Mostly parotid |
Warning signs of malignancy: facial nerve weakness with a parotid mass, pain or paresthesia, rapid growth, fixation, ulceration and cervical lymphadenopathy. Investigation is by ultrasound and fine-needle aspiration or core biopsy, then MRI or CT.
After parotidectomy: facial nerve weakness (temporary or permanent), Frey syndrome (gustatory sweating from misdirected auriculotemporal nerve fibers) and a numb earlobe from great auricular nerve injury.
Exam Traps
- A swelling of the lower lip that comes and goes is a mucocele; the upper lip is a more common site for salivary tumors than for mucoceles.
- Do not try to drain a deep, persistent palatal swelling as an "abscess" without excluding a salivary tumor.
- A palatal ulcer appearing after an injection that heals over weeks suggests necrotizing sialometaplasia, but it still needs biopsy to exclude carcinoma.
A 45-year-old reports swelling and pain under the right side of the mandible that start whenever he eats and settle within an hour. The floor of the mouth is otherwise normal. Which investigation is the most useful first image?
Sialography during the acute swelling with a large volume of contrast
Hand-wrist radiograph to assess the patient's skeletal maturity
Periapical radiograph of tooth 46 to look for apical periodontitis
Mandibular occlusal radiograph to look for a submandibular duct stone
A slowly growing, painless, firm mass has been present for three years at the junction of the hard and soft palate on the left side of a 40-year-old. The overlying mucosa is intact. Which lesion is most likely?
Torus palatinus located in the midline of the hard palate
Nicotine stomatitis with red dots over the entire palate
Pleomorphic adenoma of the minor salivary glands
Necrotizing sialometaplasia that will ulcerate within days
A patient with a firm parotid mass also has weakness of the ipsilateral lower lip and inability to close the eye on that side. What does this finding suggest?
A malignant tumor invading the facial nerve
Acute sialadenitis from dehydration, which typically resolves without treatment
A Warthin tumor, which commonly causes facial palsy
A pleomorphic adenoma, which typically causes facial palsy
Sections you finish are checked off in the contents.