Salivary Gland Inflammation and Sialadenitis

Sialadenitis is inflammation of a salivary gland, which may be acute or chronic and may result from infection, obstruction, or immune-mediated injury. It typically presents as painful swelling of an affected gland, classically the parotid or submandibular, and is among the most common salivary gland disorders.

Definition

Sialadenitis is inflammation of one or more salivary glands, classified by tempo (acute or chronic) and cause (bacterial, viral, obstructive, or autoimmune), and characterised clinically by glandular pain and swelling.

Scope

This topic covers the principal forms of salivary gland inflammation: acute bacterial (suppurative) sialadenitis, viral parotitis, chronic and obstruction-related sialadenitis, and immune-mediated sialadenitis as seen in Sjögren syndrome. It is a reference and educational account of how these inflammatory processes arise and are categorised, not clinical management guidance.

Core questions

• Is the inflammation acute or chronic, and which gland is involved?
• Is the cause infectious, obstructive, or immune-mediated?
• How does reduced salivary flow predispose to ascending bacterial infection?
• What distinguishes viral parotitis from bacterial sialadenitis on clinical grounds?

Key concepts

• Acute bacterial (suppurative) sialadenitis
• Viral parotitis
• Chronic recurrent sialadenitis
• Obstructive sialadenitis
• Autoimmune (lymphocytic) sialadenitis
• Salivary stasis and ascending infection
• Sialography and ductal imaging

Mechanisms

Acute bacterial sialadenitis usually develops when salivary flow falls, allowing oral bacteria to ascend the duct into the gland; dehydration, ductal obstruction, and reduced secretory function are recognised predisposing states. Viral parotitis, classically mumps, results from systemic viral infection of glandular tissue. Chronic sialadenitis often follows recurrent obstruction or infection, with progressive ductal dilatation, acinar atrophy, and fibrosis. In autoimmune sialadenitis, lymphocytic infiltration centred on ducts injures acinar tissue and reduces secretion, the pattern underlying Sjögren syndrome.

Clinical relevance

Inflammatory salivary disease is encountered routinely in dental and head and neck settings, where painful glandular swelling, especially when related to eating, prompts a search for an obstructive or infectious cause. This entry describes how the inflammatory categories are recognised and is educational; it does not provide diagnostic protocols or treatment recommendations.

Epidemiology

Acute bacterial sialadenitis most often affects the parotid gland and is associated with reduced salivary flow, dehydration, and debilitated states. The submandibular gland is disproportionately affected by obstructive and chronic sialadenitis because of its anatomy and viscous secretion, and sialolithiasis is a frequent underlying factor in chronic submandibular inflammation. Autoimmune sialadenitis is a defining feature of Sjögren syndrome, a common systemic autoimmune disorder.

History

Mumps parotitis has been described since antiquity, and the link between salivary stasis, obstruction, and gland infection was recognised through clinical and pathological study over the twentieth century. The characterisation of focal lymphocytic sialadenitis as the histological hallmark of Sjögren syndrome integrated salivary inflammation into the understanding of systemic autoimmune disease.

Seminal works

• kessler-part1-2018
• brito-zeron-2016

Frequently asked questions

What is the difference between acute and chronic sialadenitis?

Acute sialadenitis is a sudden, often infectious inflammation with rapid painful swelling, whereas chronic sialadenitis is a persistent or recurrent process, frequently linked to obstruction, in which the gland undergoes progressive ductal change, acinar loss, and fibrosis.

Why does reduced salivary flow increase the risk of bacterial sialadenitis?

Saliva normally flushes the ductal system; when flow falls, oral bacteria can ascend the duct into the gland, which is why dehydration, obstruction, and glandular hypofunction predispose to acute bacterial sialadenitis.