The three pairs of major salivary glands (parotid, submandibular and sublingual) are located on either side of the mouth. All of these glands produce saliva and secrete it into the mouth cavity via the salivary gland. This accounts for the majority of the saliva in the mouth. Many smaller accessory glands in the lining of the mouth and tongue also contribute moderate quantities of saliva into the mouth. Saliva secretion is constant and significantly increases during eating or as a result of seeing or smelling appetizing food.
Swelling of the salivary gland is usually unilateral (one-sided) but certain systemic causes may result in bilateral swelling. Depending on the extent of the enlargement and gland involved, the swollen gland may cause visible swelling of the face.
Other symptoms that may also be present include :
Both the major and minor salivary glands may be affected by a number of conditions thereby resulting in swelling or enlargement of the gland. This can occur for the following reasons :
1. Inflammatory and Non-inflammatory Swelling
Inflammation of a salivary gland is known as sialadenitis and results in edematous swelling of the salivary gland. It is commonly caused by infections.
Non-inflammatory swelling of a salivary glands in known as sialadenosis and is caused by hypertrophy (enlargement) of the acini and ductal atrophy (shrinking).
Dryness of the mouth, slurred speech, mouth pain (stomatodynia) and strange tastes in the mouth, usually a bad taste in the mouth (cacogeusia) often as a result of pus. A fever is usually associated with infections. An abscess may also arise and cause further enlargement of the gland.
2. Obstruction of the salivary duct
The salivary duct may be obstructed if it is inflamed, ruptured or blocked by a stone (sialolithiasis) or scar tissue. Saliva is unable to exit the gland and leaks into the surrounding salivary gland tissue and accumulates in cyst-like spaces.
A mucocele may affect both the minor and major salivary glands and its ducts. A mucocele of a minor salivary gland is often seen on the lower lip as a ‘bump’ that occurs after accidentally biting the lip. The term ranula also refers to a mucocele but usually of the glands (major or minor) on the floor of the mouth, like with the sublingual gland.
A salivary gland stone is a result of sedimentation of the chemical components of saliva. It is more likely to occur in the submandibular glands due to its thicker mucoid secretions. A minority of salivary gland stones are found in the parotid gland since its secretion is of the thinner serous type. Sublingual gland stones are rare.
Secondary bacterial infection is common therefore the signs and symptoms may be similar to the infectious causes of inflammation discussed above. In addition, pain and swelling of the affected salivary gland is worse during and immediately after a meal when saliva production increases.
Salivary gland tumors may be benign or malignant. Majority of the tumors arise in the parotid gland and minority in the submandibular glands. Tumor in the sublingual glands are rare.
Of these, most of the parotid gland tumors are benign while majority of submandibular and sublingual gland tumors are malignant (cancerous). Overall majority of tumors are therefore benign and typically present as slow growing, painless masses.
Causes of Swollen Salivary Glands
Inflammatory & Non-Inflammatory Swelling
- Parainfluenza types I and II
- Influenza A
- Staphylococcus aureus
- Streptococcus viridans
- Haemophilus influenzae
- Streptococcus pyogenes
- Escherichia coli
- Sjogren syndrome
- Diabetes mellitus
- Eating Disorders
- Lympadenopathy (parotid nodes)
- Kidney failure
Duct Obstruction and Destruction
- Salolithiasis (salivary gland duct stones)
- Impacted food debris
- Long term use of diuretics
- Chronic inflammation (repeated trauma is the most common cause)
- Pleomorphic adenoma (mixed)
- Warthin tumor
- Intraductal papilloma
- Malignant (Cancer)
- Mucoepidermoid carcinoma
- Acinic cell carcinoma
- Adenoid cystic carcinoma
- Malignant mixed tumors