Causes have not been specifically identified but the most likely are viral opportunists and autoimmune responses. Viruses linked to this can include; hepatitis C, cytomegalovirus, paramyxovirus, influenza A, and adenovirus. Treatment is anti-retroviral therapy.Disseminated histoplasmosis: During a large urban disseminated histoplasmosis outbreak (est. 100,000 victims) in Indianapolis from 1978 to 1979, manifestations included parotitis. Autoimmune causes
These are also collectively known as chronic punctate parotitis or chronic autoimmune parotitis.Sjögrens syndrome:
Chronic inflammation of the salivary glands may also be an autoimmune disease known as Sjögrens syndrome. The disease most commonly appears in people aged 40–60 years, but it may affect small children. In Sjögren syndrome, the prevalence of parotitis in women versus men is approximately 9:1. The involved parotid gland is enlarged and tender at times. The cause is unknown. The syndrome is often characterized by excessive dryness in the eyes, mouth, nose, vagina, and skin.Lymphoepithelial lesion of Godwin:
Most frequently associated with a circumscribed tumor with the histologic features of Sjögren syndrome. This designation has also fallen out of favour. Blockage
Blockage of the main parotid duct, or one of its branches, is often a primary cause of acute parotitis, with further inflammation secondary to bacterial superinfection. The blockage may be from a salivary stone, a mucous plug, or, more rarely, by a tumor, usually benign. Salivary stones (also called sialolithiasis, or salivary duct calculus) are mainly made of calcium, but do not indicate any kind of calcium disorder. Other causes can be duct stricture (narrowing of the duct), infection or injury.
Local heat applied to the gland, massaging the gland from back to front, and taking penicillin usually cure individual episodes. Treatment of individual infections may prevent injury to the gland parenchyma. Severe disease may be treated by parotidectomy.Sialadenosis (sialosis):
In this disorder, both parotid glands may be diffusely enlarged with only modest symptoms. Patients are aged 20–60 years at onset, and the sexes are equally involved. The glands are soft and non-tender. Approximately half of the patients have endocrine disorders such as diabetes, nutritional disorders such as pellagra or kwashiorkor, or have taken drugs such as guanethidine, thioridazine, or isoprenaline.Sarcoidosis:
The lungs, skin, and lymph nodes are most often affected, but the salivary glands are involved in approximately 10% of cases. Bilateral firm, smooth, and non-tender parotid enlargement is classic. Xerostomia occasionally occurs. The Heerfordt-Waldenstrom syndrome consists of sarcoidosis with parotid enlargement, fever, anterior uveitis, and facial nerve palsy.IgG4-related sialadenitis:
This term refers to IgG4-related disease (IgG4-RD) involving any of the major salivary glands, i.e. parotid or submandibular glands. This is often symmetrical and is usually associated with manifestations of IgG4-RD elsewhere in the body. IgG4-related sialadenitis is particularly associated with involvement of one or both of the lacrimal glands (referred to as IgG4-related dacryo-sialadenitis). Mikuliczs disease, now considered to be a subtype of IgG4-related disease, was a term used when (i) any two of the parotid, submandibular and lacrimal glands were persistently and symmetrically enlarged and (ii) other diseases that may mimic this presentation were excluded. Pneumoparotitis:
Air within the ducts of the parotid gland with or without inflammation.