Sialadenitis
Updates to Article Attributes
Sialadenitis refers to inflammation of the salivary glands. It may acute or chronic and has a wide range of causes.
Clinical presentation
Patients may present with painful swelling of the concerned salivary gland, after eating (salivary colic). In bacterial sialadenitis they may be an purulent discharge.
Pathology
Aetiology
Sialadenitis can occur in various forms ranging from acute bacterial sialadenitis (acute suppurative sialadenitis) to acute viral sialadenitis to chronic sialadenitis.
Acute sialadenitis is most commonly caused by an ascending bacterial infection, with staphylococcus aureus or streptococcus viridans being the most common organisms 2,8,9. Sialolithiasis is often present (causing obstructive sialadenitis) and is stones are found in ~85% of submandibular ducts and ~15% of parotid ducts 1,7,9. Other causes of acute sialadenitis include dehydration, immunosuppression, iatrogenic (drug-induced) and rarely haematogenous spread 10.
Epidemic parotitis is associated with the mumps virus, occurs mostly in children and is mostly bilateral 10.
Other conditions associated with sialadinitis include:
- Sjogren syndrome - chronic sialadenitis 2
- Mikulicz syndrome - chronic sialadenitis 2
- post radiation - post-irradiative sialadenitis 4
- Iodine 131 administration 3
Distribution
Due to calculi being a dominant etiologicalaetiological factor, the distribution of sialadenitis follows that of sialolithiasis and therefore the submandibular glands are the most commonly affected.
Radiographic features
Fluoroscopy
Sialography is contra-indicated in acute sialadenitis because it can worsen the infection 2.
Ultrasound
In acute sialadenitis the affected gland appears enlarged, hypoechoic and hyperaemiac on ultrasound 8,10.
In chronic infective forms the affected gland appears atrophic and diffusely hypoechoic with irregular margins - the ultrasound appearances have been likened to that of a “cirrhotic” liver 8.
There may be evidence of sialectasis if recurrent.
CT
Acute sialadenitis:
- enlarged salivary gland with abnormal attenuation, indistinct margin and vivid contrast enhancement with associated adjcacent fat stranding and/or thickening of deep cervical fasciathat is typically unilateral 2,9,10
- dilated duct from sialolithiasis or stenosis 9
- enlarged intra- or extra-glandular lymph nodes may also be seen but this is non-specific and can occur in other conditions such as malignancy 2
- abscesses are hypodense fluid collections, which may or may not be loculated 10
MRI
The salivary gland(s) is often enlarged. The affected gland can range from well defined to poorly defined. Signal characterisitcs in majority of cases tend to be heterogenous 6.
Signal characteristics include
-
T1
- acute sialadenitis - low signal 10
- chronic sialadenitis - inhomogeneous low signal 10
-
T2 -
- acute sialadenitis - overall signal tends to be high 6
- chronic sialadenitis - overall signal may to low to intermediate due to fibrosis 6
Differential diagnosis
Differential conditions to keep in mind include 10:
See also
-</ul><h5>Distribution</h5><p>Due to calculi being a dominant etiological factor, the distribution of sialadenitis follows that of <a href="/articles/sialolithiasis">sialolithiasis</a> and therefore the <a href="/articles/submandibular-glands">submandibular glands</a> are the most commonly affected.</p><h4>Radiographic features</h4><h5>Fluoroscopy</h5><p>Sialography is contra-indicated in acute sialadenitis because it can worsen the infection <sup>2</sup>.</p><h5>Ultrasound</h5><p>In acute sialadenitis the affected gland appears enlarged, hypoechoic and hyperaemiac on ultrasound <sup>8,10</sup>.</p><p>In chronic infective forms the affected gland appears atrophic and diffusely hypoechoic with irregular margins - the ultrasound appearances have been likened to that of a “cirrhotic” liver <sup>8</sup>.</p><p>There may be evidence of <a href="/articles/sialectasis">sialectasis</a> if recurrent.</p><h5>CT</h5><p>Acute sialadenitis:</p><ul>- +</ul><h5>Distribution</h5><p>Due to calculi being a dominant aetiological factor, the distribution of sialadenitis follows that of <a href="/articles/sialolithiasis">sialolithiasis</a> and therefore the <a href="/articles/submandibular-glands">submandibular glands</a> are the most commonly affected.</p><h4>Radiographic features</h4><h5>Fluoroscopy</h5><p>Sialography is contra-indicated in acute sialadenitis because it can worsen the infection <sup>2</sup>.</p><h5>Ultrasound</h5><p>In acute sialadenitis the affected gland appears enlarged, hypoechoic and hyperaemiac on ultrasound <sup>8,10</sup>.</p><p>In chronic infective forms the affected gland appears atrophic and diffusely hypoechoic with irregular margins - the ultrasound appearances have been likened to that of a “cirrhotic” liver <sup>8</sup>.</p><p>There may be evidence of <a href="/articles/sialectasis">sialectasis</a> if recurrent.</p><h5>CT</h5><p>Acute sialadenitis:</p><ul>
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