Granulomatosis with polyangiitis may have areas of liquefaction necrosis caused by vasculitis. A triad of vasculitis, necrosis and granulomatous inflammation may be observed. In secondary Sjogren’s syndrome, periglandular fibrosis with the absence of inflammation may also be observed in addition to that of Myoepithelial sialadenitis from the progressive systemic sclerosis. Sarcoid has tight epithelioid granulomas and lymphoid infiltrate. Chronic Sclerosing Sialadenitis has peridutcal fibrosis with a dense lymphoplasmacytic infiltrate with lymphoid follicles. Eosinophils may be seen. Diagnosis
According to the British Medical Journal (The BMJ) Best Practice on Sialadenitis, there are multiple factors to consider during the diagnosis of sialadenitis, including history, presenting signs and symptoms, followed by appropriate investigations in relation to the presenting case. Other factors to also consider include the type of gland affected as well as underlying conditions such as an autoimmune disease or ductal stones. Acute bacterial sialadenitis
May present with a history of recent surgical intervention or use of medications such as antihistamines, antidepressants, or anticholinergic agents. These medications may lead to objective hypofunction or subjective feeling of a dry mouth without hypofunction. There may also be a history of decrease in salivary volume secondary to a systemic disease. A unilateral or bilateral painful swelling of the parotid or submandibular regions may be present upon a physical examination. This could be accompanied by an external displacement of the earlobe usually adjacent to an inflamed parotid gland. Pus suppuration from major salivary gland duct openings may occur spontaneously or after manipulation of the affected gland.
Respiratory distress – this could present in the form of stridor, use or reliance on accessory muscles of respiratory, nasal flaring, or wheeze. These signs may develop if glandular swelling is significant enough, resulting in airway obstruction. 3. Cranial nerve palsy – swelling increases the risk of compression of cranial nerves VII, IX and XII. Other diagnostic factors which are less common
1. Connective tissue disorder or Sjogren’s syndrome – history of Sjogren’s syndrome, or a concomitant connect tissue disorder such as systemic lupus erythematosus, rheumatoid arthritis, or scleroderma. 2. Recurrent painless swellings – indicative of underlying autoimmune aetiology. 3. Displacement of earlobe – may be present when swelling of the parotid gland is present. 4. Prodrome of tingling in the affected gland
5. Swelling on hard palate

Diagnostic tests
Tests available as part of diagnosing sialadenitis include:

Culture and sensitivity testing of exudate from salivary duct. Culturing of purulent discharge is advisable in acute presentations of sialadenitis to allow targeted antibiotic therapy. Full blood count if infection is suspected. Facial radiographs such as dental radiographic views should be taken to exclude an obstructive element due to presence of sialolith or evolving abscess. However, sialoliths with low calcium phosphate content may not be visible. Treatment
In chronic recurrent sialadenitis or chronic sclerosing sialadenitis, acute attacks are managed with conservative therapies such as hydration, analgesics (mainly NSAIDs), sialogogues to stimulate salivary secretion, and regular, gentle gland massage. If infection is present, appropriate cultures should be obtained, followed by empirical antibiotic therapy initially, for example amoxicillin/clavulanate or clindamycin which cover oral flora.