Standard, and most effective, therapy to date is glandular sialadenectomy, which is associated with fairly low operative morbidity; however, in recent times, the administration of steroid (which can shrink the inflammatory lesion and is known to reduce serum IgG4 values) has been considered favorably, and may be useful in younger patients or those who refuse surgery.

The cause and pathogenesis of this chronic condition are not very well understood. Several factors have been postulated:

- Formation of a hard salivary calculus or sialolith by accumulation of calcium salts in the duct of the salivary gland (a process known as Sialolithiasis). This has been proposed as the most common cause for Küttner's tumor of the submandibular gland, with sialoliths observed in an appreciable proportion of cases. However, sialolith involvement may not be found in many cases.

- Abnormalities of the salivary gland ducts leading to excessive accumulation or retention of ductal secretions, which can excite chronic inflammations.

- Immune, especially autoimmune, cause - which has gained steam, given the observation that the tissue of the glands is overrun with lymphoid immune cells and fibrous connective tissue, as well as corroboration from markedly similar lesions (with histologic and immunohistochemical findings) seen elsewhere in the body. The presence of abundant Immunoglobulin G4 (IgG4) associated with Plasma cells infiltrating into the salivary glands, as well as increased serum IgG4 concentration, has been noted with patients with Küttner's tumor.

This chronic condition is primarily observed in adult (40–70 years) patients. However, Küttner's tumor, with prominent immunopathological features, has been described in an 11-year-old boy in Brazil in 2012.

In 80% of cases, the parotid gland is affected. Lacrimal glands are also affected.

Benign lymphoepithelial lesion is a type of benign enlargement of the parotid and/or lacrimal glands. This pathologic state is sometimes, but not always, associated with Sjögren's syndrome.

Some specific reactive lymphadenopathies with a predominantly follicular pattern:

- Rheumatoid arthritis

- Sjogren syndrome

- IgG4-related disease (IgG4-related lymphadenopathy)

- Kimura disease

- Toxoplasmosis

- Syphilis

- Castleman disease

- HIV-associated lymphadenopathy

- Progressive transformation of germinal centers (PTGC)

Infections involving the salivary glands can be viral or bacterial (or rarely fungal).

- Mumps is the most common viral sialadenitis. It usually occurs in children, and there is preauricular pain (pain felt in front of the ear), swelling of the parotid, fever, chills, and headaches.

- Bacterial sialadentitis is usually caused by ascending organisms from the oral cavity. Risk factors include reduced salivary flow rate.

- Human immunodeficiency virus-associated salivary gland disease (HIV-SGD).

Follicular hyperplasia (or "reactive follicular hyperplasia" or "lymphoid nodular hyperplasia") is a type of lymphoid hyperplasia. It is caused by a stimulation of the B cell compartment. It is caused by an abnormal proliferation of secondary follicles and occurs principally in the cortex without broaching the lymph node capsule. The follicles are cytologically polymorphous, are often polarized, and vary in size and shape. Follicular hyperplasia is distinguished from follicular lymphoma in its polyclonality and lack of bcl-2 protein expression, whereas follicular lymphoma is monoclonal, and does express bcl-2).

IOI or orbital pseudotumor is the second most common cause of exophthalmos following Grave’s orbitopathy and the third most common orbital disorder following thyroid orbitopathy and lymphoproliferative disease accounting for 5–17.6% of orbital disorders, There is no age, sex, or race predilection, but it is most frequently seen in middle-aged individuals. Pediatric cases account for about 17% of all cases of IOI.

A salivary diverticulum (plural "diverticuli") is a small pouch or out-pocketing of the duct system of a major salivary gland. Such diverticuli typically cause pooling of saliva and recurrent sialadenitis, especially parotitis. A diverticulum may also cause a sialolith to form.

The condition can be diagnosed by sialography. Affected individuals may "milk" the salivary gland to encourage flow of saliva through the duct.

The cause is currently unknown. The histology is suggestive of an autoimmune reaction. The high rate of relapses as well as relatively high proportion of bilateral cases is highly suggestive of a systemic predisposition.

Presently most evidence points towards an important role of elevated prolactin levels or overt hyperprolactinemia with additional triggers such as local trauma or irritation. Alpha 1-antitrypsin deficiency was documented in one case, interferon-alpha therapy in another case. Similar cases of granulomatous mastitis were reported in IgG4-related disease though the exact relationship to IGM remains to be elucidated. Other contributing factors of IGM were investigated such as oral contraceptives usage. Many cases were reported after use of prolactin elevating medications such as antipsychotics.

Elevated prolactin levels have the direct effects of increasing secretory activity of breast lobules, maintaining tight junctions of the ductal epithelium, preventing involution of the breast gland after weaning and are known to stimulate the immune system, contributing to both physiological and pathological granulomatous lesions and non-caseating granulomas. PRL is also secreted locally in the breast and local secretion by lymphocytes may be enhanced during inflammatory reactions.

Autoimmune reaction to extravasated fat and protein rich luminal fluid (denaturized milk) resulting from the secretory activity is assumed to be one of the triggers of IGM. Several other hormones can contribute to PRL signaling in the breast gland, high levels of insulin caused for example by peripheral insulin resistance (resulting from pregnancy, gestational diabetes or developing diabetes mellitus type 2) will enhance the galactogenic and antiapoptotic effects of PRL and growth hormone by acting synergistically with IGF-1.

This is a rare condition, probably caused by an allergic reaction, in which there is sudden swelling of the salivary glands. It is associated with other allergic conditions such as asthma, urticaria, allergic rhinitis and food allergy.

Riedel's thyroiditis is classified as rare. Most patients remain euthyroid, but approximately 30% of patients become hypothyroid and very few patients are hyperthyroid. It is most seen in women.

Sialodochitis (also termed ductal sialadenitis), is inflammation of the duct system of a salivary gland. This is compared to sialadenitis, which is inflammation of the gland parenchyma.

Sialodochitis may be associated with salivary duct strictures and salivary stones.

It is common in both the parotid glands and submandibular glands.

The treatment is as for sialadenitis.

Plasma cell granuloma is a lesional pattern of inflammatory pseudotumour, different from the "inflammatory myofibroblastic tumor" pattern.

It is linked to IgG4-related disease.

As the number of published cases of AIP has increased, efforts have been focused on defining AIP as a distinct clinical and pathologic entity and toward developing some generally agreed upon diagnostic criteria and nomenclature. Terms frequently encountered are autoimmune or autoimmune-related pancreatitis, lymphoplasmacytic sclerosing pancreatitis, idiopathic tumefactive chronic pancreatitis, idiopathic pancreatitis with focal irregular narrowing of the main pancreatic duct, and non-alcoholic duct destructive chronic pancreatitis. There are also a large number of case reports employing descriptive terminology such as pancreatitis associated with Sjögren’s syndrome, primary sclerosing cholangitis, or inflammatory bowel disease. Some of the earliest cases were reported as pancreatic pseudotumor or pseudolymphoma.

Multifocal fibrosclerosis and idiopathic fibrosclerosis are disorders of unknown aetiology, characterised by fibrous lesions (co-)occurring at a variety of sites. Known manifestations include retroperitoneal fibrosis, mediastinal fibrosis and Riedel's thyroiditis.

They are now considered to be manifestations of IgG4-related disease.

The exact cause of IOI is unknown, but infectious and immune-mediated mechanisms have been proposed. Several studies have described cases where onset of orbital pseudotumor was seen simultaneously or several weeks after upper respiratory infections. Another study by Wirostko et al. proposes that organisms resembling Mollicutes cause orbital inflammation by destroying the cytoplasmic organelles of parasitized cells.

Orbital pseudotumor has also been observed in association with Crohn’s disease, systemic lupus erythematosus, rheumatoid arthritis, diabetes mellitus, myasthenia gravis, and ankylosing spondylitis all of which strengthen the basis of IOI being an immune-mediated disease. Response to corticosteroid treatment and immunosuppressive agents also support this idea.

Trauma has also been seen to precede some cases of orbital pseudotumor. However, one study by Mottow-Lippe, Jakobiec, and Smith suggests that the release of circulating antigens caused by local vascular permeability triggers an inflammatory cascade in the affected tissues.

Although these mechanisms have been postulated as possible causes of IOI, their exact nature and relationships to the condition still remain unclear.

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.

If there are attacks more than approximately 3 times per year or severe attacks, surgical excision of the affected gland should be considered.

These are also collectively known as chronic punctate parotitis or chronic autoimmune parotitis.

"Sjögren's syndrome:"

Chronic inflammation of the salivary glands may also be an autoimmune disease known as Sjögren's 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.

Sialadenitis (sialoadenitis) is inflammation of a salivary gland. It may be subdivided temporally into acute, chronic and recurrent forms.

Idiopathic granulomatous mastitis is defined as granulomatous mastits without any other attributable cause such as those above mentioned. It occurs on average two years and almost exclusively up to six years after pregnancy, usual age range is 17 to 42 years. Some cases have been reported that were related to drug induced hyperprolactinemia.

Exceptionally rarely it has been diagnosed during pregnancy and in men.

"Acute bacterial parotitis:"

is most often caused by a bacterial infection of Staphylococcus aureus but may be caused by any commensal bacteria.

"Parotitis as Extrapulmonary Tuberculosis:"

The mycobacterium that cause tuberculosis can also cause parotid infection. Those infected tend to have enlarged, nontender, but moderately painful glands. The diagnosis is made by typical chest radiograph findings, cultures, or histologic diagnosis after the gland has been removed. When diagnosed and treated with antitubercular medications, the gland may return to normal in 1–3 months.

"Acute viral parotitis (mumps):"

The most common viral cause of parotitis is mumps. Routine vaccinations have dropped the incidence of mumps to a very low level. Mumps resolves on its own in about ten days.

"HIV parotitis:" Generalized lymphadenopathy has long been associated with HIV, but the localized enlargement of the parotid gland is less well known.

IgG4-related ophthalmic disease (IgG4-ROD) is the recommended term to describe orbital (eye socket) manifestations of the systemic condition IgG4-related disease, which is characterised by infiltration of lymphocytes and plasma cells and subsequent fibrosis in involved structures. It can involve one or more of the orbital structures.

Frequently involved structures include the lacrimal glands, extraocular muscles, infraorbital nerve, supraorbital nerve and eyelids. It has also been speculated that ligneous conjunctivitis may be a manifestation of IgG4-related disease (IgG4-RD).

As is the case with other manifestations of IgG4-related disease, a prompt response to steroid therapy is a characteristic feature of IgG4-ROD in most cases, unless significant fibrosis has already occurred.

As recognition of IgG4-RD is relatively recent, there are limited studies on its epidemiology. It is therefore difficult to make an accurate estimation of prevalence. Furthermore, age of onset is almost impossible to estimate; age at diagnosis is frequently misused as the age of onset.

A 2011 study estimated the incidence of IgG4-RD in Japan at 2.8–10.8/million population, with a median age of onset of 58 years.

Salivary gland aplasia (also termed salivary gland agenesis) is the congenital absence of salivary glands. Usually the term relates to the absence of some or all of the major salivary glands.

It is a rare condition, and most known cases have been in association with syndromes of the ectodermal tissues, particularly the lacrimal apparatus. Example syndromes which have been reported with salivary gland aplasia include hereditary ectodermal dysplasia, mandibulofacial dysostosis and hemifacial microsomia.

The main significance of the condition is a lack of saliva, causing xerostomia (dry mouth), with accompanying susceptibility to dental caries (tooth decay), infections of the mouth, and upper respiratory tract infections (e.g., candidiasis, ascending sialadenitis, laryngitis and pharyngitis). Patients with salivary gland aplasia typically require regular application of topical fluoride to prevent tooth decay.