Version May 2024
INTRODUCTION — Salivary gland swelling is frequently encountered by clinicians and has a variety of causes. The major salivary glands include the paired parotid, submandibular, and sublingual glands which are collectively responsible for the production of over 95 percent of saliva. In addition, there are approximately 1000 minor salivary glands dispersed through the submucosa of the oral cavity, with each measuring from 1 to 2 mm in size (figure 1). This discussion will address the evaluation and diagnostic approach to salivary gland swelling in adults, focusing mainly on the parotid and submandibular glands.
DEFINITIONS
●Sialadenitis is inflammation of a salivary gland.
●Acute sialadenitis is characterized by sudden enlargement and pain of the affected gland and is usually due to an obstructive, infectious, or inflammatory etiology. The size of the affected gland may fluctuate depending on the specific cause and acuity of the inflammation. (See 'Acute salivary gland swelling' below.)
●Chronic sialadenitis, in general, is less likely to be painful and is often characterized by an abnormally firm gland that may be enlarged, normal, or even atrophic in size. (See 'Chronic salivary gland swelling' below.)
●Sialosis (or sialadenosis) is a multifocal (usually bilateral), noninflammatory, non-neoplastic enlargement of the salivary glands (typically the parotid glands) that is often associated with systemic metabolic conditions. (See 'Sialosis due to metabolic causes' below.)
EPIDEMIOLOGY — Estimates regarding the prevalence of nontumor salivary gland swelling in the general population are largely imprecise and likely under-reported. A report from a national health data set in Poland from 2010 to 2019 identified 230,000 patients with "salivary gland pathologies" in whom 85 percent were nonneoplastic [1]. These investigators suggested that the prevalence of salivary gland inflammatory lesions was about 1.2 percent of the general population and that salivary stones are responsible for up to 50 percent of such inflammatory sialadenitis. Autopsy reports yield similar estimates [2]. Other reports cite an incidence of one per 15,000 to 30,000 [3], or one per 10,000 to 20,000 population [4].
INITIAL EVALUATION — There are many algorithms available to guide the evaluation of salivary gland swelling [5]. This presentation focuses on the duration of symptoms (acute versus chronic) as a primary criterion to direct diagnostic decision making. We subsequently categorize the causes according to the number of salivary glands involved (unifocal versus multifocal). Any system of classification will be imperfect in that there is inevitable overlap between designations, but we find these categories to be clinically useful.
The clinical history is essential in assessing salivary gland swelling [6]. Key factors to address include:
●Duration of symptoms (acute versus chronic)
●Number of glands involved (unifocal versus multifocal)
Additional necessary clinical information includes:
●Discomfort associated with the swelling
●Foul taste in the mouth
●Provocative factors (eg, association with meals or salivary stimulants)
●Persistent versus intermittent or recurrent symptoms
●Constitutional symptoms (eg, fever, viral prodrome, weight loss)
●Systemic symptoms (eg, joint pain, dry eyes and mouth)
●Medical comorbidities (eg, alcohol use, diabetes, bulimia, autoimmune disease, liver disease), history of radiation treatment (local external beam radiation therapy or I-131 treatment), recent receipt of intravenous contrast dye, new medications
The physical examination provides useful information to further guide the diagnostic evaluation. Key elements of the examination include visual inspection of the glands, palpation (including a bimanual examination with a finger in the oral cavity), massage of the gland with attempted expression of saliva, and an otologic examination if there is any complaint of ear pain. In addition, a focused cranial nerve (CN) examination should be performed to evaluate CN V (the trigeminal nerve) and CN VII (the facial nerve); with parotid gland swelling, all branches of the facial nerve may be affected (picture 1), but if swelling affects only the submandibular gland, involvement is generally limited to the marginal mandibular branch (picture 2).
When examining the salivary glands, specific physical examination findings to note include:
●Number of glands involved (unifocal versus multifocal)
●Gland size (ie, enlarged, normal, atrophic)
●Gland texture (ie, smooth, soft or firm, nodular, discrete mass)
●Gland tenderness
●Erythema of the overlying skin
●Type of salivary discharge expressed from salivary ductal orifice with massage of gland (ie, normal [thin and watery], mucoid, purulent, bubbly, reduced, or absent) (movie 1 and movie 2)
Additionally, there are many processes involving adjacent anatomic structures that may mimic salivary gland swelling, and a careful physical examination can often distinguish these entities from actual salivary gland swelling. (See 'Processes that may mimic salivary gland enlargement' below.)
APPROACH TO IMAGING IN SALIVARY GLAND SWELLING — Imaging is used as an important part of the evaluation of salivary gland swelling.
For the majority of patients with unifocal salivary gland swelling (acute and chronic), additional evaluation with imaging is indicated. Imaging may also be indicated for patients with other presentations of salivary gland swelling to evaluate the nature of the swelling (cystic versus diffuse enlargement) or to determine if the salivary gland itself or another structure (eg, an embedded or nearby lymph node) is enlarged. (See 'Processes that may mimic salivary gland enlargement' below.)
We typically perform initial imaging with ultrasound; however, the quality of salivary gland ultrasound is highly dependent upon operator technique, and in facilities with less experience and expertise in salivary gland ultrasound, computed tomography (CT) with contrast is an alternative first-line imaging to ultrasound. If a patient is unable to receive intravenous contrast, a CT without contrast is acceptable. Some prefer CT without contrast to avoid mistaking contrast-enhanced vascular structures for stones, but we prefer the additional soft tissue definition provided with concurrent use of contrast.
While ultrasound and CT generally provide good detail of the ductal system and gland, if a neoplasm or a vascular lesion of the salivary gland is suspected (based upon the clinical history, the physical examination, or previous imaging studies), we generally obtain magnetic resonance imaging (MRI); MRI is the most sensitive imaging modality for evaluation of most neoplasms and vascular lesions of the salivary glands [7]. MRI may also be used to specifically evaluate ductal anatomy via MR sialography.
Other techniques used include to visualize the ducts include sialography and sialendoscopy, procedures typically performed by otolaryngologists. Sialography, a procedure where the salivary ductal orifice is cannulated and a small amount a radio-opaque contrast material is injected into the ductal system, provides the greatest detail of the salivary ductal system. However, it is not as widely used as other methods due to the technical nature of the procedure which requires expertise and special equipment.
Sialendoscopy is a procedure which uses a small camera to allow direct visualization of the ducts and also allows removal of stones and foreign bodies.
Our imaging approach in patients with unifocal salivary gland swelling is as follows:
●If proximal ductal dilatation is identified on ultrasound, we proceed with CT with contrast. We do not generally perform sialography for submandibular salivary stones, as surgical treatment decisions can generally be made with modifications to the approach made based on intraoperative findings regard strictures. Conversely, when parotid stones are identified on CT imaging, we perform sialography to evaluate for strictures; this information provides a preoperative 'road-map' for the ductal system and helps determine the most appropriate surgical approach (intra-oral versus open) and the potential for preserving the gland.
●If ultrasound is performed and no abnormality is identified, we perform CT with contrast acknowledging its greater sensitivity in detecting stones [8]; sialography or sialendoscopy may be then performed if needed. The contrast does not help in detecting stones but does assist in identifying associated findings such as lymphadenopathy and sialadenitis.
●If CT with contrast is performed as the initial imaging test, and abnormalities of the ductal system are found such as obstruction with stone(s) or stricture(s), sialography and/or sialendoscopy may then be indicated.
●If a mass with features suggesting a neoplasm or vascular etiology is detected on ultrasound or CT, then we may obtain an MRI in many cases to further define the extent.
ACUTE SALIVARY GLAND SWELLING — Swelling of a salivary gland may be considered acute if the duration is less than several weeks. The onset and duration of symptoms vary according to etiology. As examples, the symptoms of obstructive sialadenitis develop in seconds and may last for days, while infectious sialadenitis develops over hours to days. We place conditions which typically cause intermittent, recurring salivary gland swelling within this category.
Acute unifocal salivary gland swelling — Acute, unifocal salivary gland swelling is most commonly due to obstruction, with sialolithiasis (salivary gland stones) often cited as the most common cause. Ductal strictures are also a common cause of obstruction, either in isolation or in association with stones. Other common causes of acute unifocal swelling include bacterial infection and inflammation following external beam radiation. The cause (obstruction, bacterial infection or post-radiation) can often be determined based upon clinical history and physical examination.
For patients who present with acute, unifocal salivary gland swelling, we first assess for the presence of infection; fever, significant gland tenderness, and purulent saliva expressed from the ductal orifice are typically seen in bacterial sialadenitis. The timing of symptoms can help determine if the bacterial infection is primary or secondary to obstruction:
●In primary bacterial sialadenitis, the process may develop over hours to days, and fever will typically be present at the onset of swelling. The patient may complain of a foul taste in the mouth, and massage of the gland may reveal purulent saliva at the ductal orifice (movie 3). (See 'Infectious causes' below and "Suppurative parotitis in adults", section on 'Clinical manifestations'.)
●If bacterial sialadenitis occurs secondary to ductal obstruction, obstructive symptoms may be present for days before infection develops, although the time course is variable. Signs and symptoms of a bacterial infection in the setting of obstruction include increasing gland size and pain, development of purulent saliva (although saliva may be absent if the duct is completely obstructed), and development of fever. (See 'Obstructive causes' below.)
If there is a concern for bacterial infection, we first perform ultrasound and may also perform CT with contrast to differentiate diffuse suppurative parotitis from abscess and to identify an underlying cause such as a stone that may elude ultrasound detection. (See 'Approach to imaging in salivary gland swelling' above and "Suppurative parotitis in adults", section on 'Clinical manifestations'.)
In the absence of infection, patients with acute unifocal salivary gland swelling due to obstruction will typically present with an enlarged, tender gland without overlying skin erythema or warmth. The onset of swelling generally occurs within seconds of salivary stimulation (such as eating or smelling food). On examination, massage of the gland may reveal reduced salivary production from the duct orifice. The saliva may be clear or may appear mucoid if proximal changes to the gland have resulted from chronic or recurrent obstruction. Additional evaluation is typically not needed for an initial episode of obstruction that improves with conservative measures. However, in the case of recurrent obstruction (two or more lifetime episodes) or obstructive sialadenitis not responding quickly to conservative therapy, imaging is needed to see if stones, strictures, or both are present. (See 'Obstructive causes' below and 'Approach to imaging in salivary gland swelling' above.)
A patient with acute, unifocal salivary gland swelling due to external beam radiation will have a history of this exposure; we do not typically perform salivary gland imaging in these patients in the absence of signs or symptoms of acute obstruction or infection. (See 'Inflammatory causes' below.)
Obstructive causes — Acute unifocal salivary gland swelling due to obstructive sialadenitis is usually caused by salivary gland stones and/or strictures and is characterized by intermittent gland swelling classically occurring with the stimulation of meals. The mechanical obstruction of salivary flow within the duct causes swelling of the gland as saliva is produced but is unable to drain normally. Obstructive sialadenitis is diagnosed by imaging. (See 'Approach to imaging in salivary gland swelling' above.)
Initial conservative treatment for sialadenitis due to obstruction from any cause includes sialagogues (salivary stimulants such as sour candy), local heat, oral hydration, and massage of the involved gland (movie 1 and movie 2). Improvement in symptoms will typically happen quickly (within one to five days) in the majority of patients.
The value in the use of sialogogues and gland massage is generally limited to those cases with either partial ductal obstruction or obstruction that is relieved with these interventions; with unresolved complete obstruction, these treatments may only increase pain if salivary drainage is not restored. (See "Salivary gland stones", section on 'Primary care management'.)
A single minor (transient and without significant pain) episode of salivary gland swelling is sufficiently common that imaging and a referral to an otolaryngology is usually not required. However, multiple (two or more lifetime) minor episodes or a single episode characterized by significant pain (with or without infection) warrant consultation with an otolaryngologist for further evaluation [9].
In the case of long-term duct obstruction (with or without recurrent episodes of acute swelling), the affected gland may ultimately become atrophic (figure 2).
Obstructive causes of salivary gland swelling include:
●Sialolithiasis (salivary stones) – Sialolithiasis, or "concrements in the efferent ducts of the salivary glands" [10], is the most common cause of acute, unifocal salivary gland swelling. The clinical presentation of acute obstructive sialadenitis due to stones is variable depending on the degree of obstruction; symptoms may be less severe and episodic or more severe and persistent. The presentation, evaluation, and management of salivary gland stones is discussed in detail elsewhere. (See "Salivary gland stones".)
●Ductal stricture – Salivary ductal stricture is a narrowing in the salivary duct lumen that impairs normal salivary flow. Strictures may be characterized as either single or multiple, and discrete or diffuse.
Ductal stricture often presents similarly to sialolithiasis, although the overall course may typically be more of relapsing and remitting symptoms. Ultrasound may help identify ductal stenosis with the indirect finding of proximal duct dilation, but it is not sensitive enough to rule out ductal stenosis [11]. The sensitivity of ultrasound can be enhanced by stimulation of salivary secretions with sialogogues such as sour candy or vitamin C [12]. However, sialography is more sensitive than ultrasound not only for identifying duct stenosis but also for characterizing the extent and the number of stenoses present [13]. In our experience, contemporary dynamic fluoroscopic sialography with duct cannulation and radiocontrast insufflation offers the highest-quality assessment of duct anatomy and may additionally be therapeutic in the course of performing a hydrodilation with 'flushing out' [14]. Recent reports identify the capacity to substitute gadolinium as an adequate contrast agent for patients unable to tolerate iodinated contrast [15].
Determining the etiology of a salivary duct stricture may be difficult; all disorders associated with salivary duct injury including irradiation, trauma, prior infection, and autoimmune processes may result in duct damage and ultimate stricture. However, the cause for the stricture often remains unknown.
For patients with acute salivary gland swelling due to ductal stricture, we recommend initial treatment with conservative measures, including hydration, sialagogues, and massage. As with other causes of obstructive sialadenitis, if there is any concern for the development of a secondary infection, appropriate antibiotic therapy (including coverage for Staphylococcus aureus) should be started and the patient referred to otolaryngology. (See "Salivary gland stones", section on 'Primary care management'.)
For patients with recurrent (two or more lifetime episodes) or persistent symptoms despite conservative treatment (generally, a period of weeks to months depending on severity of symptoms), we advise referral to otolaryngology for consideration of other treatment options, including steroid infusion, botulinum toxin injection, ductal dilatation, sialendoscopy, and rarely ductal reconstruction or sialadenectomy (image 1).
When salivary gland stones occur in the presence of ductal strictures, the management of the stone is often more difficult, requiring intervention such as sialendoscopy with ductal dilatation and stone removal.
●Ductal foreign body – A foreign body may infrequently enter the salivary ducts in a retrograde fashion from the oral cavity to cause obstruction; fish bones, grass blades, hair, and toothbrush bristles have been found within salivary ducts [16]. Foreign bodies within the ducts may additionally serve as a nidus for the development of a sialolith, as seen in a Chinese hospital where in a series of 561 sialendoscopies, 423 sialoliths were identified, 2.8 percent of which were found to contain fish bones [17].
Such foreign bodies, if not identified on ultrasound or CT, would be identified on sialography and then removed via sialendoscopy.
Rarely, foreign bodies may be introduced percutaneously into the ductal system traumatically, also requiring sialendoscopy for removal [18].
●Pneumoparotitis – Sialadenitis may result when air is forced into the duct and gland (termed "pneumoparotitis" when it affects the parotid gland). It has been described in association with the use of positive pressure ventilation [19,20] and activities that cause increased intraoral pressure, including wind instrument playing [21], glass blowing, exercising, and behaviors associated with psychiatric abnormalities [22].
"Anesthesia mumps," with swelling of the submandibular glands, has been described following perioperative continuous positive airway pressure (CPAP) ventilation for surgical airway management [19].
Pneumoparotitis can occur as a result of oronasal CPAP. The obstruction is caused by the air within the duct and should resolve within a few hours after discontinuation of the positive airway pressure ventilation or conversion from oronasal CPAP to nasal CPAP [20,23]. However, air may remain within the gland longer and the resulting sialadenitis may take several days (or longer, depending on the severity of the inflammation) to resolve.
Pneumoparotitis is suspected in patients with the above risk factors, although some patients with self-induced disease may fail to report the precipitating events. On physical examination, expressed saliva from the affected duct may appear "bubbly"; on ultrasound, air is identified within the ducts and gland.
Pneumoparotitis is typically an acute process, lasting only as long as the precipitating event. If chronic or recurrent, however, it may lead to ductal changes causing chronic or recurrent obstruction and possibly chronic infection and inflammation [24].
●External compression of the duct – Less common causes of obstruction to salivary flow may occur from other processes including pressure from denture flanges impacting the submandibular duct orifice [25], from an enlarged mandible, or from a hypertrophied masseter causing kinking of the parotid duct [26,27].
Infectious causes — Bacterial infections are a common infectious cause of acute, unilateral salivary gland swelling. Less frequent causes include mycobacterial infections and actinomycosis.
●Bacterial sialadenitis – Bacterial sialadenitis typically involves the parotid or submandibular glands. It is characterized by the sudden onset of pain and swelling of a single salivary gland, with an indurated, tender, and swollen gland on physical examination. Massage of the gland may produce purulent material at the duct orifice (picture 3 and movie 3). Predisposing factors include any process that inhibits salivary flow or causes salivary stasis, such as dehydration, sialolithiasis, ductal stricture, autoimmune disease (ie, Sjögren's disease) and prior irradiation [28]. Other risk factors include older age, poor oral hygiene, use of anticholinergic agents, intubation or positive pressure oral mask ventilation, and postoperative state. The microbiology and treatment of bacterial sialadenitis is discussed in detail elsewhere. (See "Suppurative parotitis in adults", section on 'Microbiology' and "Suppurative parotitis in adults", section on 'Treatment'.)
●Other causes – Other less common causes of infectious sialadenitis include actinomycosis [29,30] and mycobacteria [31-36]. While mycobacterial infections of the lymph nodes (tuberculous lymphadenitis) typically involve the cervical lymph nodes, in rare cases the salivary gland itself may become involved. (See "Cervicofacial actinomycosis", section on 'Clinical manifestations' and "Cervicofacial actinomycosis", section on 'Treatment' and "Tuberculous lymphadenitis", section on 'Cervical lymphadenopathy'.)
Inflammatory causes — Acute, unifocal salivary gland swelling may develop from external beam radiation, which is most often administered as part of cancer treatment. If multiple salivary glands are included in the radiation field, then multifocal salivary gland swelling may develop.
●Post-radiation sialadenitis – The acute effects of radiation can cause an inflammatory sialadenitis with swelling and pain that usually resolves over a period of months [37]. Following the initial radiation-induced sialadenitis, chronic destructive changes to the glands usually result in gland atrophy associated with symptomatic xerostomia. The long-term effects of radiation are generally irreversible.
Although acute swelling resulting from external beam irradiation is more likely to occur from damage to the gland parenchyma, it may occur less frequently from ductal obstruction associated with duct narrowing. Occasionally, radiation will induce ductal stricture, which can become symptomatic if the gland resumes salivary production. (See 'Obstructive causes' above.)
Acute multifocal salivary gland swelling — Acute, multifocal salivary gland swelling may be due to viral (ie, mumps or mumps-like) or inflammatory (ie, systemic radioiodine treatment, contrast-induced sialadenitis) causes, juvenile recurrent parotitis (JRP), or drug effect.
Mumps sialadenitis should be suspected based upon a patient's clinical presentation of acute multifocal salivary gland swelling accompanied by constitutional symptoms, including fever, headache, malaise, and myalgia. Laboratory evaluation will confirm the diagnosis in the majority of cases.
JRP is a recurrent parotitis of unknown etiology that primarily affects the pediatric population. Acute multifocal salivary gland swelling, particularly in a child with a history of prior similar episodes, usually represents JRP. The usual presentation is that of recurrent inflammation of one or both parotid glands with erythema and warmth of the overlying skin, accompanied by fever and malaise.
Acute sialadenitis due to radioiodine therapy or intravenous iodinated contrast dye is strongly suspected based upon an absence of constitutional symptoms and a recent exposure to one of these agents.
Viral sialadenitis — Salivary swelling in association viral infection (viral sialadenitis) is well documented for multiple viruses. Viruses known to be associated with salivary gland swelling include paramyxovirus (causing mumps), human immunodeficiency virus (HIV), Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpes simplex virus (HHSV-8), hepatitis C virus (HVC), human papilloma virus (HPV), coxsackie virus, influenza virus, and echovirus [38,39].
●Mumps – Mumps is a contagious viral illness caused by the mumps virus, and is characterized by fever, headache, malaise and myalgia, followed by the development of salivary gland (typically parotid) swelling within 48 hours of symptom onset. Although often unilateral at onset, parotid gland swelling and inflammation becomes bilateral in over 90 percent of cases within a few days [40]. Diagnoses of mumps is confirmed by laboratory testing. (See "Mumps", section on 'Clinical manifestations' and "Mumps", section on 'Diagnosis'.)
●Other viral causes (mumps-like) – Other viral infections are associated with clinical parotitis and may mimic mumps infection. In pediatric patients, Epstein-Barr virus (EBV) and parainfluenza virus (PIV) were found to be the most common causes of mumps-like viral infections, with adenovirus, enterovirus, parvovirus, and herpes virus type 6 (HHV-6) also identified as causes [41]. (See "Mumps", section on 'Differential diagnosis'.)
●Coronavirus disease 2019 (COVID-19) – The negative impact of COVID-19 on smell and taste is well established (see "COVID-19: Clinical features"). Although there is evidence for salivary swelling (sialadenitis) associated with acute COVID-19 infection, the evidence for long-term impact is less conclusive and reports of COVID-associated chronic sialadenitis are much less than for chronic xerostomia [42-44]. Although salivary swelling reflecting sialadenitis has been reported as an 'early' symptom associated with COVID-19 infection [43], the perceived salivary swelling may not actually reflect a sialadenitis, but rather intraparotid lymphadenitis [45].
Inflammatory causes — Inflammatory causes of acute, multifocal salivary gland swelling include radioiodine (131-I) therapy and receipt of intravenous iodinated contrast dye. The development of acute, painful, multifocal salivary gland swelling following administration either of these agents is highly suggestive of the cause; in the absence of other symptoms or likely etiologies, no further diagnostic evaluation is typically needed if symptoms resolve as expected.
●Radioiodine treatment (131-I) – Radioiodine treatment (131-I), used therapeutically in both the treatment of differentiated thyroid carcinomas as well as hyperthyroidism, can cause inflammation of the salivary glands. (See "Differentiated thyroid cancer: Radioiodine treatment" and "Radioiodine in the treatment of hyperthyroidism".)
Acute sialadenitis with pain, swelling, and xerostomia may develop in 25 to 67 percent of patients receiving 131-I treatment [46-49], with those receiving a higher dose of radiation more likely to develop acute sialadenitis.
Symptoms of salivary gland inflammation typically begin within hours of receiving 131-I therapy, and the acute symptoms generally resolve within several days.
Management of the acute salivary gland inflammation associated with 131-I therapy includes massage, warm compresses, oral hydration, and sialogogues. For patients with severe symptoms, glucocorticoids may rarely be required. Management of radioiodine sialadenitis is discussed in detail elsewhere. (See "Differentiated thyroid cancer: Radioiodine treatment", section on 'Sialadenitis'.)
131-I therapy commonly induces ductal stricture years after treatment; although the salivary gland may atrophy in response to therapy, the ductal stricture may be symptomatic if the narrowing becomes tighter as the gland continues salivary production (image 2) (see 'Obstructive causes' above). A 2021 study of sialography in patients with radioiodine sialadenitis identified ductal strictures in all 30 patients [50]. Duct dilation with or without steroid insufflation has been supported as viable treatment option potentially done in clinic but more often done via sialendoscopy [51]. A more recent update analyzing sialendoscopy proved its benefit in improving quality of life in patients with sialolithiasis, but raised questions about its efficacy in radioiodine induced stenosis [52].
●Contrast-induced sialadenitis – Rapid, painless enlargement of the salivary glands ("iodide mumps") may rarely occur shortly after infusion of iodinated contrast dye [53].
The risk of developing contrast-induced sialadenitis is associated with high serum iodide levels (>10 mg/100 mL) and is more likely to occur with impaired renal function due to reduced elimination of contrast material [54]. It has been reported that the high concentration of iodine dye in salivary glands results in local inflammation and edema leading to blockage of the salivary duct [55].
Symptoms usually resolve rapidly, within hours to a few days. Treatment includes hydration and, if needed, nonsteroidal antiinflammatory drugs (NSAIDs) [55]. For patients with severe symptoms that do not resolve quickly, systemic glucocorticoids may be used [53,55]. Treatment with dialysis is another management option for patients with severe symptoms, but we would only offer this if severe symptoms persisted despite the above treatments.
Juvenile recurrent parotitis — JRP is a recurrent, acute parotitis characterized by intermittent painful swelling of one or both glands and redness of the overlying skin and is often accompanied by fever [56]. Episodes of swelling typically last from 24 to 48 hours but may last for up to one to two weeks and, rarely, longer [57].
JRP most often occurs in boys between the ages of four months and 15 years and is generally self-limited with spontaneous remission of episodes at puberty [57]. The majority of patients are free of symptoms by age 22. Prior to the decrease in incidence of mumps, among children, JRP had been the second most common salivary gland disorder after mumps; however, it may now be more common [56].
The diagnosis of JRP is made based upon the patient's history, with laboratory tests used to exclude other conditions such as mumps, Sjögren's disease, and sarcoidosis, with imaging tests used to confirm the diagnosis if necessary [58]. There is not, however, a widely accepted set of guidelines required to establish the diagnosis.
Recommended laboratory testing includes antinuclear antibodies (anti-Ro/SSA and anti-La/SSB) and measurement of angiotensin-converting enzyme (ACE) level, which are all normal in JRP. Ultrasound helps to support the diagnosis, demonstrating heterogeneous glandular tissue with nodular hypoechoic areas, and is the preferred initial imaging test. Other imaging modalities (computed tomography [CT], magnetic resonance imaging [MRI], sialography, and sialendoscopy) may be useful if additional diagnostic evaluation is necessary [57,58]. (See "Diagnosis and classification of Sjögren’s disease", section on 'Antibodies to Ro/SSA and La/SSB' and 'Approach to imaging in salivary gland swelling' above and "Overview of extrapulmonary manifestations of sarcoidosis", section on 'Parotid and salivary glands'.)
The pathogenesis of JRP is unclear, with various causes hypothesized, including autoimmune disease, retrograde infection (bacterial or viral) of the ducts, genetic abnormality, and congenital ductal malformation. (See 'Obstructive causes' above.)
JRP falls under the broad category of non-suppurative, nonobstructive parotid inflammation, but it is possible that it will be further subdivided if specific, individual causes are identified.
Drug-induced sialadenitis — Drug-induced parotitis is a rare adverse drug reaction associated with l-asparaginase, clozapine, and phenylbutazone [59]. The mechanism of action for drug-induced salivary swelling is largely unknown but may include spasm of smooth muscle within the gland, altered autonomic effect with interference in sympathetic vasoconstrictor effect, and anticholinergic effect [60].
Acute sialadenosis of bulimia nervosa — Although chronic parotid gland enlargement is widely described in patients with bulimia nervosa [61-64], cessation of purging (ie, vomiting) may result in acute sialadenosis, characterized by painful, bilateral parotid gland swelling [65]. Symptoms are typically managed with warm compresses, NSAIDS, and sialagogues as need until the discomfort resolves.
CHRONIC SALIVARY GLAND SWELLING — We consider swelling of a salivary gland to be chronic when it has been present for weeks to months, although there are no well-established guidelines defining the transition from "acute" to "chronic." The causes of chronic salivary gland swelling are diverse and include benign tumor, malignant tumor (either primary or metastatic), immune-mediated, infectious (HIV-related), or an infiltrative process.
Chronic unifocal salivary gland swelling — A common etiology of chronic, unifocal salivary gland swelling is tumor (benign or malignant). The rate of enlargement of the affected salivary gland will vary depending upon the particular tumor. Imaging is required as part of the initial evaluation in all patients with chronic, unifocal salivary gland swelling (see 'Approach to imaging in salivary gland swelling' above), and if tumor is suspected, most patients with chronic unifocal salivary gland swelling will need a biopsy of the affected gland, usually by ultrasound guided fine needle aspiration biopsy. Ultrasound guided core needle biopsy will be needed in selected cases [66].
Tumor — Salivary gland swelling may reflect the development of a primary salivary gland tumor or the presence of a tumor metastasis from another primary site. Lymphomas may develop within the salivary gland parenchyma (picture 4) but may also develop within lymph nodes embedded in a salivary gland. (See 'Processes that may mimic salivary gland enlargement' below.)
Primary tumors of the salivary glands may be benign or malignant. Tumors of different histologic subtypes may present with symptoms including pain, paresthesia, and facial nerve paralysis but most commonly as a painless mass. Accelerated enlargement a previously stable growth may represent malignant transformation of a benign tumor. Primary tumors of the salivary glands are discussed elsewhere. (See "Salivary gland tumors: Epidemiology, diagnosis, evaluation, and staging" and "Pathology of head and neck neoplasms", section on 'Salivary gland tumors'.)
In addition to primary tumors, metastases to the parotid gland commonly occur from cutaneous malignancies in the head and neck area, including melanoma and squamous cell carcinoma [67,68]. (See "Surgical management of primary cutaneous melanoma or melanoma at other unusual sites", section on 'Head and neck' and "Locally advanced squamous cell carcinoma of the head and neck: Approaches combining chemotherapy and radiation therapy".)
Polycystic parotid disease — Sclerosing polycystic adenosis (SPA), or polycystic dysgenic disease, is a rare pseudoneoplastic condition of unknown etiology resulting in cystic changes, fibrosis, and epithelial proliferation within the salivary glands [69].
SPA typically occurs within the parotid gland, but may be also seen in the submandibular gland, and develops as a slow-growing mass. Patients often experience a mild pain or a tingling sensation, and the affected gland may be mildly tender on examination, with multiple firm, rubbery nodules ranging from a few millimeters to as large as 7 cm [70]. As with other salivary gland masses of uncertain etiology, a biopsy is needed for diagnosis.
On microscopic examination, there may be difficulty in distinguishing these rare lesions from mucoepidermoid carcinomas, low-grade adenocarcinomas, benign adenomas, and mixed tumors.
In multiple case reports and small series, SPAs have been described as histologically similar to adenosis of the breast with a lobular arrangement, and ductal epithelial hyperplasia with atypia or dysplasia to invasive carcinoma [71]. The etiology of SPA remains unknown, although there may be an association with the Epstein-Barr virus (EBV) [72]. SPA and is considered by some to be a neoplasm rather than a reactive process due to its atypical and dysplastic microscopic features, with a recurrence rate cited as high as 30 percent [73]. Malignant transformation is also possible.
The recommended treatment for polycystic parotid disease is complete excision via superficial parotidectomy [71].
Chronic multifocal salivary gland swelling — Causes of chronic, multifocal salivary gland swelling include metabolic sialosis, immune mediated processes (eg, Sjögren's disease, immunoglobulin G4-related disease [IgG4-RD]), granulomatous sialadenitis (eg, sarcoidosis, polyangiitis with granulomatosis), and amyloidosis. In such patients, a careful clinical history to determine the presence of other symptoms (eg, sicca syndrome, chronic rhinosinusitis, arthritis) or risk factors for sialosis (eg, diabetes, bulimia, alcohol use) is essential. Blood work, including autoantibodies, specific immunoglobulin levels, and angiotensin-converting enzyme (ACE) level can often confirm the diagnosis in immune-mediated and granulomatous sialadenitis. Biopsy of the clinically affected gland (or a minor labial salivary gland if amyloidosis or Sjögren's disease is suspected) can be performed if blood tests are not diagnostic. In the case of sialosis, where the condition is suspected based upon comorbidities and risk factors, and for which there are no diagnostic laboratory tests, ultrasound can be used to confirm the diagnosis.
Sialosis due to metabolic causes — Sialosis, also known as sialadenosis, is defined as chronic enlargement of the salivary parenchyma with gradually progressive swelling that does not fluctuate and is unassociated with the stimulus of eating [74]. Although it typically presents as painless bilateral parotid enlargement, it may occasionally affect the submandibular glands and be associated with mild discomfort [75].
Approximately half of all cases are associated with one of the recognized risk factors, including diabetes, metabolic syndrome, alcoholism, bulimia, malnutrition, and liver disease [76-79]. With the rising prevalence of obesity and diabetes, sialosis is seen with increasing frequency and may now be the most common cause of salivary gland swelling in the United States [74,80,81]. As an example, in a study of 200 patients with diabetes or pre-diabetes, 24 percent had parotid gland enlargement due to sialosis [82].
Sialosis due to alcohol and diabetes may have a similar clinical presentation, but histologically alcoholic sialosis is associated with enlarged acini and minimal parenchymal fat content, while diabetic sialosis is associated with smaller acini and greater fatty infiltration [83-85]. The buildup of secretory granules seen in the acinar cells may be responsible for enlargement of the gland parenchyma. As the process matures, acinar enlargement may give way to fatty infiltration of the gland [86,87]. When discomfort does occur in association with sialosis, it may be due to the pressure and necrosis of the enlarged acini.
Sialosis should be suspected based upon the patient's clinical history (ie, the presence of risk factors) and physical examination. Ultrasound, which will show diffuse enlargement of the major salivary glands with a greater than normal hyperechoic and homogeneous echotexture [88] can be done to help support the diagnosis. If the clinical history, examination and ultrasound are consistent with sialosis, then no further evaluation is needed. However, if there is associated pain, fluctuation in salivary gland size, progressive gland enlargement, or involvement of the minor salivary glands, referral to otorhinology is indicated for further evaluation.
Treatments used for the management of the discomfort and swelling associated with sialosis include steroid insufflation, oral pilocarpine drops, tympanic neurectomy, botulinum toxin injection, and, rarely, salivary gland resection [77,89,90].
The primary management of sialosis involves addressing the underlying disorder, although complete resolution of gland enlargement does not always occur.
Immune-mediated sialadenitis
●Sjögren's disease – Sjögren's disease is a chronic systemic autoimmune disease characterized by lymphocytic infiltration of the exocrine glands, with resultant dry eyes, dry mouth, salivary gland swelling, and less commonly, extraglandular abnormalities [91]. (See "Diagnosis and classification of Sjögren’s disease".)
The degree of salivary gland swelling among patients with Sjögren's disease is variable, with some patients having primarily extraglandular manifestations and others having significant salivary gland enlargement. However, almost all patients with salivary gland swelling due to Sjögren's disease will also describe dry eyes and dry mouth. Salivary gland involvement with Sjögren's disease may also include painful swelling associated with ductal obstruction from scarring, mucus plugs, and a higher propensity to stone formation. The diagnosis of Sjögren's disease is reviewed in detail elsewhere. (See "Diagnosis and classification of Sjögren’s disease", section on 'Diagnostic tests'.)
Among patients with primary Sjögren's disease, there is an estimated 5 to 10 percent lifetime risk of developing non-Hodgkin lymphoma (extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, also called MALT lymphoma), with >60 percent arising within the parotid gland [92,93]. Clinicians should be aware of this increased risk and consider lymphoma as the cause of new salivary gland enlargement in a patient with known Sjögren's disease. (See "Clinical manifestations of Sjögren’s disease: Extraglandular disease", section on 'Lymphoma'.)
We manage the painful salivary gland swelling that may accompany Sjögren's disease with hydration, gland massage, and pain medication (nonsteroidal antiinflammatory drugs [NSAIDs], acetaminophen) if needed. Alternative treatment with systemic glucocorticoids (oral prednisone) in consultation with the treating rheumatologist may be considered for patients whose symptoms do not respond to conservative therapy. For patients with Sjögren's disease and recurrent episodes of painful sialadenitis, we perform sialography to determine if there are strictures in the main duct and assess the extent of parenchymal damage [94]. When strictures in the main or secondary ducts are present, they may respond to dilation (usually under general anesthesia with sialendoscopy) along with steroid insufflation. If there are no significant strictures, treatment with steroid insufflation can be offered [95-97].
Insufflation of the parotid glands with steroid through duct cannulation as an in-clinic procedure has been useful to address swelling and pain associated with Sjögren's disease [97]. A similar approach has been reported as useful to address xerostomia associated with Sjögren's disease and radioiodine sialadenitis [98].
Strong support for treatment for chronic sialadenitis associated with Sjögren's disease as well as other causes has been addressed with ultrasound-guided botulinum toxin injection to the glans [99].
Management of xerostomia in Sjögren's disease is discussed elsewhere. (See "Treatment of dry mouth and other non-ocular sicca symptoms in Sjögren’s disease".)
●IgG4-related disease – IgG4-RD) is an immune-mediated fibro-inflammatory process most frequently involving the pancreas and salivary glands but often involving other exocrine glands, lymph nodes, and multiple other organs [100]. (See "Clinical manifestations and diagnosis of IgG4-related disease".)
Patients with IgG4-related sialadenitis (IgG4-RS) present with persistent painless parotid and/or submandibular gland swelling (previously known as Küttner tumor or sclerosing sialadenitis) which is usually but not always bilateral (picture 5) [101]. There may be associated lacrimal gland swelling, and approximately 15 percent of patients have evidence of concurrent autoimmune pancreatitis [102]. The painless growth of sclerosing sialadenitis may present like a neoplasm [103,104]. (See "Clinical manifestations and diagnosis of IgG4-related disease", section on 'Head and neck disease'.)
The diagnosis may be suspected based upon clinical features and the results of laboratory testing and imaging findings but is confirmed by biopsy of the affected gland. On histologic examination, there is prominent infiltration of IgG4-expressing plasmacytes in lacrimal and salivary glands [105].
IgG4-RD has similarities with Sjögren's disease, but it differs in several ways (table 1) [100]. IgG4-RD is more likely to occur in males and present with persistent (rather than intermittent) salivary gland swelling, and less likely to be associated with salivary gland dysfunction, elevated antinuclear antibodies and rheumatoid factor, and abnormalities on sialography.
Oral corticosteroids, typically prednisone, are the first-line treatment of choice for IgG4-RS. For those patients with symptoms that are not responsive to systemic steroid therapy treatment with other immunomodulators may be indicated. Surgical removal of the salivary glands is a less commonly used option [103,104,106,107]. (See "Treatment and prognosis of IgG4-related disease".)
●Kussmaul disease – Kussmaul disease is a rare disorder characterized by painful swelling of the parotid and/or submandibular glands, resulting from obstruction of the salivary ducts by mucofibrinous plugs [108]. This disorder, also termed "sialodochitis fibrinosa," is characterized by [109]:
•Recurring episodes of major salivary gland swelling
•Discharge of mucofibrinous plugs with a high content of eosinophils from salivary ducts
•Elevated levels of serum IgE and/or eosinophilia
•Presence of concomitant asthma or allergic rhinitis
•Irregular dilation of the main salivary ducts on imaging (sialography or magnetic resonance imaging [MRI])
•Peri-ductal lymphocytic infiltrates and abundant eosinophils on salivary gland biopsy
Kussmaul disease is believed to be an allergic process; it is treated with antihistamines, systemic glucocorticoids, leukotriene receptor antagonists and had included trials of immunomodulators [110] and possibly duct dilation with steroid insufflation [111].
Granulomatous sialadenitis (noninfectious) — Granulomas represent a tissue response characterized by a collection of macrophages, epithelioid cells, lymphoid cells, and multinucleate giant cells [112]. Non-necrotizing salivary gland granulomas may result from a foreign body, or may represent a foreign-body type response to tumor, including acinic cell carcinoma, Warthin tumor, or lymphoepithelial lesions [112]. Other etiologies of non-necrotizing granulomatous sialadenitis include autoimmune, allergic, vasculitis and idiopathic [113].
●Sarcoidosis ─ Sarcoidosis is a multisystem disorder of unknown etiology that can involve the parotid and other salivary glands. Among patients with sarcoidosis, 5 to 30 percent may have parotid swelling [114-117]. Salivary gland swelling is typically painless, and can be unifocal or multifocal [118]. (See "Overview of extrapulmonary manifestations of sarcoidosis", section on 'Parotid and salivary glands'.)
Heerfordt-Waldenström syndrome is an uncommon variant of sarcoidosis characterized by anterior uveitis, enlargement of the parotid glands with accompanying facial nerve paralysis (due to compression of the nerve by an enlarged parotid gland), and occasionally, fever [119]. Glucocorticoids are the initial treatment for sarcoidosis. (See "Overview of extrapulmonary manifestations of sarcoidosis", section on 'Vision outcomes' and "Treatment of pulmonary sarcoidosis: Initial approach", section on 'Patients with more severe or progressive disease'.)
●ANCA-associated vasculitides ─ Patients with antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitides, including granulomatosis with polyangiitis (GPA) and eosinophilic granulomatosis with polyangiitis (EGPA), may occasionally develop salivary gland involvement with clinically apparent swelling of the affected glands.
•Granulomatosis with polyangiitis – Salivary gland swelling, occasionally painful, has been reported in 1 to 4 percent of patients with GPA, with one or multiple glands affected [120,121]. In addition, GPA may infrequently present with isolated salivary gland enlargement before the appearance of systemic symptoms or renal involvement [122-124]. (See "Granulomatosis with polyangiitis and microscopic polyangiitis: Clinical manifestations and diagnosis", section on 'Other manifestations'.)
Treatment of GPA is discussed elsewhere. (See "Granulomatosis with polyangiitis and microscopic polyangiitis: Induction and maintenance therapy", section on 'Initial treatment approach'.)
•Eosinophilic granulomatosis with polyangiitis – Salivary gland involvement in EGPA is uncommon and, when present, usually occurs in the presence of other symptoms. In rare cases, however, multifocal swelling of all four major salivary glands may be a prominent presenting complaint [125]. Treatment with glucocorticoids is the primary treatment. (See "Clinical features and diagnosis of eosinophilic granulomatosis with polyangiitis (Churg-Strauss)" and "Eosinophilic granulomatosis with polyangiitis (Churg-Strauss): Treatment and prognosis", section on 'Systemic glucocorticoids'.)
●Xanthogranulomatous sialadenitis ─ Xanthogranulomatous tissue reactions (characterized by lipid-laden macrophages with granulomatous component that includes epithelioid and multinucleated giant cells) may present as a mass suggestive of a neoplasm. It is typically a chronic, painless enlargement, but in the salivary gland, it may be more acute if ductal obstruction or adjacent inflammation occurs. Within the parotid gland, xanthogranulomatous tissue reactions have been identified in association with inflammatory processes or tumors [126]. In addition, a xanthogranulomatous reaction may develop following fine-needle aspiration [127].
HIV related — Among patients with HIV infection, 1 to 10 percent will develop salivary gland enlargement, often involving the parotid gland [128]. This may be related to inflammation or infectious or neoplastic processes but most commonly results from benign lymphoepithelial cysts (BLEC) [129]. Individuals with HIV infection and BLEC usually develop chronic, painless bilateral parotid swelling not typically accompanied by xerostomia.
Ultrasound patterns of parotid enlargement in patients with HIV infection includes lymphocytic aggregations, lymphoepithelial cysts, and lymphadenopathy [130]. When identified, cystic enlargement of the parotid gland warrants investigation for possible HIV infection.
Antiretroviral therapy (ART) is the cornerstone of therapy for BLEC and is often successful in decreasing the size of the cysts [128]. For large cysts that persist despite ART, ultrasound-guided fine-needle aspiration may be done to rule out the coexistence of a malignancy as well as to decrease the size of the cyst. Management options for those patients with significant cosmetic deformity that persists despite ART include repeated cyst aspirations, sclerosing therapy, radiation therapy [131,132], and surgical excision of the affected gland(s).
Infiltrative causes — An infiltrative cause of chronic, multifocal salivary gland swelling is amyloidosis.
Amyloidosis — Localized major salivary gland involvement with amyloidosis is rare, with reports of amyloidomas (tumor-like accumulations of amyloid) of the parotid and submandibular glands [133-135]. Treatment may involve excision of the affected gland (if appropriate), and systemic therapy aimed at the underlying cause of the amyloidosis. (See "Overview of amyloidosis", section on 'Treatment'.)
Idiopathic causes — The idiopathic causes of chronic, multifocal salivary gland swelling are rare and include inflammatory myofibroblastic tumor, Kimura disease, and Rosai-Dorfman disease.
●Inflammatory myofibroblastic tumor – Inflammatory myofibroblastic tumor (inflammatory pseudotumor, plasma cell granuloma, fibrous histiocytoma) is a rare benign neoplasm that most frequently occurs in the lungs and orbit but also may develop in the neck, skull base, thyroid, liver, parotid gland or other organs [136,137]. (See "Inflammatory myofibroblastic tumor (plasma cell granuloma) of the lung".)
Inflammatory myofibroblastic tumor of the parotid presents as a slow growing mass, and ultrasound will demonstrate a hypoechoic mass. Biopsy is essential to the diagnosis; spindle cells, plasma cells, and lymphocytes are key histologic findings [138].
Complete surgical resection is the usually the treatment of choice. (See "Inflammatory myofibroblastic tumor (plasma cell granuloma) of the lung", section on 'Treatment'.)
●Kimura disease – Kimura disease is a rare, chronic inflammatory disease of unknown etiology that is characterized by painless subcutaneous nodular lesions in the head and neck accompanied by enlarged cervical lymph nodes. The orbits, nasal sinuses, oral cavity, and parotid glands may also be involved. It most commonly occurs in Southeastern Asian males in the third decade of their life [139]. (See "Angiolymphoid hyperplasia with eosinophilia and Kimura disease", section on 'Epidemiology' and "Angiolymphoid hyperplasia with eosinophilia and Kimura disease", section on 'Clinical manifestations'.)
The histology includes abnormal inflammatory cellular infiltrate with eosinophils, follicular hyperplasia, and vascular infiltration [140]. Surgical excision is the initial treatment, although recurrence is common. Subsequent medical treatment with corticosteroids, cyclosporine, and other immunosuppressive therapies have been tried with limited success. Radiation treatment following surgery has been reported to be more effective than medical treatment [141]. (See "Angiolymphoid hyperplasia with eosinophilia and Kimura disease", section on 'Treatment'.)
●Rosai-Dorfman disease – Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) is a rare non-Langerhans cell histiocytosis characterized by painless lymphadenopathy (typically cervical), with frequent involvement of extranodal sites including the salivary glands [142-146].
Histologically, in Rosai-Dorfman disease, a mixed inflammatory background with plasma cells and lymphocytes with varying degrees of stromal fibrosis is seen, along with the hallmark "Rosai-Dorman cells" [147]. These are large, polygonal S-100 protein-positive histiocytes with emperipolesis (also known as lymphophagocytosis), a phenomenon characterized by the presence of lymphocytes or other inflammatory cells seen within the cytoplasm.
Although complete and spontaneous remission may occur, in a few cases the disease follows an aggressive course and may be fatal [148]. There are international consensus guidelines for the evaluation and management of Rosai-Dorfman disease [149].
PROCESSES THAT MAY MIMIC SALIVARY GLAND ENLARGEMENT — Due to the proximity of the salivary glands to various anatomical structures, enlargement or changes in other local sites may mimic salivary gland swelling. These abnormalities are often identified as part of the evaluation for apparent salivary gland enlargement. Ultrasound will typically distinguish between true salivary gland enlargement and other abnormalities, but computed tomography (CT) or magnetic resonance imaging (MRI) are often performed if further detail is needed. (See 'Approach to imaging in salivary gland swelling' above.)
●Masseter hypertrophy – Masseter muscle enlargement may be bilateral or unilateral and, if unilateral, may present with facial asymmetry and be confused with parotid enlargement (figure 3).
Masseter enlargement has been attributed to bruxism, temporomandibular joint dysfunction, and malocclusion [150,151]. Muscle enlargement from other causes should be considered, including neoplastic, inflammatory, myopathies, and vascular malformations [152-154]. In many cases, however, the etiology of masseter enlargement remains unknown.
Treatment of masseter hypertrophy is discussed elsewhere. (See "Botulinum toxin for cosmetic indications: Treatment of specific sites", section on 'Masseteric hypertrophy'.)
●Vascular malformations – Vascular malformations may present as salivary gland swelling, and the malformations may be present within or adjacent to a gland. The swelling may fluctuate, can be positional (ie, increasing in size with head down) and pain may or may not be present [155].
Initial evaluation with ultrasound is appropriate and may be diagnostic. However, further detailed examination with CT or MRI is typically needed (figure 4).
If treatment is indicated for patient discomfort or cosmesis, options include surgical removal, injection of sclerosing agents, or laser therapy [156,157].
●Branchial cleft cyst – First arch branchial cleft cysts (specifically Type I) are uncommon but may present clinically as parotid swelling due to passage of the cyst through the gland (figure 5 and image 3) [158]. Patients may develop recurrent swelling, occasionally associated with drainage from a fistula tract. When present, cysts are more likely to become symptomatic in childhood [159,160]. Treatment is surgical excision [161]. (See "Differential diagnosis of a neck mass", section on 'Branchial cleft cyst'.)
●Salivary gland lymphadenopathy – Due to embryologic timing of lymphocyte migration and lymph node formation, there are multiple intra-parotid lymph nodes, but none within the capsule of the submandibular gland. However, there are multiple lymph nodes adjacent to the submandibular gland which, when enlarged, are often mistaken for enlargement of the gland itself. Similarly, enlargement of the peri-parotid lymph nodes may mimic parotid gland swelling [162]. Ultrasound can distinguish lymph node involvement from gland enlargement as the cause of apparent salivary gland swelling.
Salivary gland lymphadenopathy may have various causes, including tumor (eg, lymphoma and metastatic carcinoma), and infections, such as cat scratch disease, toxoplasmosis, and tuberculosis. (See "Microbiology, epidemiology, clinical manifestations, and diagnosis of cat scratch disease", section on 'Lymphadenopathy' and "Toxoplasmosis: Acute systemic disease", section on 'Lymphadenopathy' and "Tuberculous lymphadenitis", section on 'Cervical lymphadenopathy'.)
●Melkersson-Rosenthal syndrome – This rare disorder is characterized by a fissured tongue, swollen lip(s), recurrent episodes of orofacial edema, and unilateral facial paralysis (picture 6) [163]. Although Melkersson-Rosenthal syndrome does not directly affect the major salivary glands, the facial swelling may mimic parotid enlargement [164].
The etiology remains uncertain; infectious agents, genetic factors, allergic reactions, and benign lymphogranulomatosis have all been implicated [165]. Connection to autoimmune disorders with overlapping features with systemic lupus erythematosus, scleroderma, and polymyositis have led some to consider it an early manifestation of mixed connective tissue disease [166]. Biopsy of edematous tissue reveals noncaseating granulomas grouped around blood vessels [167]. (See "Hereditary angioedema (due to C1 inhibitor deficiency): Pathogenesis and diagnosis", section on 'Cutaneous and/or upper airway swelling'.)
Treatment includes topical or intralesional steroids for persistent mucosal symptoms. (See "Cheilitis", section on 'Treatment'.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: IgG4-related disease" and "Society guideline links: Sjögren's disease".)
SUMMARY AND RECOMMENDATIONS
●Definition – Swelling of the salivary glands may be due to many causes. Acute sialadenitis is characterized by sudden enlargement and pain of the affected gland and is usually due to an obstructive, infectious, or inflammatory etiology. Chronic sialadenitis, in general, is less likely to be painful and is often characterized by an abnormally firm gland that may be enlarged, normal, or even atrophic in size. (See 'Definitions' above.)
●Initial evaluation – In addition to evaluating the duration of symptoms (acute versus chronic) to direct diagnostic decision making, we also consider the number of salivary glands involved (unifocal versus multifocal) in our diagnostic evaluation. Other important elements to consider include associated discomfort, provocative factors, and systemic and constitutional symptoms (such as fever, joint pain, dry eyes, and dry mouth). A careful physical examination includes examination of the glands (for size, texture, and tenderness), evaluation of expressed saliva after gland massage (movie 1 and movie 3), and evaluation of the overlying skin. (See 'Initial evaluation' above.)
●Imaging – We use imaging as an important part of the evaluation of salivary gland swelling, and it is indicated for the majority of patients with unifocal salivary gland swelling (both acute and chronic). Imaging may also be indicated for patients with other presentations of salivary gland swelling. (See 'Approach to imaging in salivary gland swelling' above.)
•We typically perform initial imaging with ultrasound; however, the quality of salivary gland ultrasound is highly dependent upon operator technique, so computed tomography (CT) with contrast is an alternative first-line imaging to ultrasound. If a neoplasm or a vascular lesion of the salivary gland is suspected, we generally obtain magnetic resonance imaging (MRI).
•Other techniques used include to visualize the gland and ducts include sialography and sialendoscopy; sialography involves fluoroscopic imaging of the ducts, while sialendoscopy allows direct visualization of the ducts and also allows removal of stones and other foreign bodies. (See 'Approach to imaging in salivary gland swelling' above.)
●Acute salivary gland swelling – Swelling of a salivary gland may be considered acute if the duration is less than several weeks. The onset and duration of symptoms vary according to etiology. (See 'Acute salivary gland swelling' above.)
•Acute, unifocal salivary gland swelling is most commonly due to obstruction, with sialolithiasis (salivary gland stones) often cited as the most common cause. Ductal strictures are also a common cause of obstruction, either in isolation or in association with stones. Other common causes of acute unifocal swelling include bacterial infection and inflammation following external beam radiation. (See 'Acute unifocal salivary gland swelling' above.)
•Acute, multifocal salivary gland swelling may be due to viral (ie, mumps or mumps-like) or inflammatory (ie, systemic radioiodine treatment, contrast-induced sialadenitis) causes, juvenile recurrent parotitis (JRP), drug effect, or cessation of purging in bulimia nervosa. (See 'Acute multifocal salivary gland swelling' above.)
●Chronic salivary gland swelling – We consider swelling of a salivary gland to be chronic when it has been present for weeks to months, although there are no established guidelines defining the transition from "acute" to "chronic." (See 'Chronic unifocal salivary gland swelling' above.)
•A common etiology of chronic, unifocal salivary gland swelling is tumor (benign or malignant); the rate of enlargement of the affected gland will vary depending upon the particular tumor. (See 'Chronic unifocal salivary gland swelling' above.)
•The most common causes of chronic, multifocal salivary gland swelling include metabolic sialosis, immune mediated processes (eg, Sjögren's disease, immunoglobulin G4-related disease [IgG4-RD]), granulomatous sialadenitis (eg, sarcoidosis, polyangiitis with granulomatosis), amyloidosis, and HIV-related. (See 'Chronic multifocal salivary gland swelling' above.)
●Processes that mimic salivary gland swelling – Due to the proximity of the salivary glands to various anatomical structures, enlargement or changes in other local sites may mimic salivary gland swelling. (See 'Processes that may mimic salivary gland enlargement' above.)
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