In Viral sialadenitis, vacuolar changes are seen in the acini with lymphocytic and monocytic infiltrate found in the interstitium
Cytomegalovirus (CMV) sialadenitis may show no gross symptoms
Chronic sialadenitis (also known as lymphoepithelial sialadenitis (LESA)) presents with 50% of which are monoclonal by PCR while mucosa-associated lymphoid tissue (MALT) lymphoma has ducts surrounded by broad coronas of monocytoid cells, infiltration of interfollicular region by monocytoid cells or atypical plasma cells containing Dutcher bodies, monoclonality by immunohistochemistry or flow cytometry, and monocytoid infiltrates in regional lymph nodes.Histologically, chronic sialadenitis can appear from unremarkable to a firm tan with expansion or atrophy of the lobular structure depending on the degree of inflammation and chronicity. Salivary stones (Sialolith) may be evident with cystic dilation of the salivary ducts and periductal fibrosis. Mucus extravasation may also be observed. Common observations of chronic sialadenitis include chronic inflammatory infiltrate (lymphocytes, plasma cells and macrophages), fibrosis, acinar atrophy, mucous cell metaplasia of the ductal system is observed. In Sialoithiasis, concomitant squamous metaplasia may be observed in the salivary ducts with dark calcific stone fragments. Chronic sialadenitis
Chronic sclerosing sialadenitis has various degrees of inflammation which can include focal lymphocytic sialadenitis to widespread salivary gland cirrhosis with obliteration of acini. This can be a result of obstruction of salivary ducts by microliths (due to associated intercurrent infections), or a result of immune reaction with the formation of secondary lymph follicles. Chronic sclerosing sialadenitis is characterised by presence of three major criteria of dense lymphoplasmacytic infiltrate, storiform pattern of fibrosis and obliterative phlebitis.
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.