Salivary gland disorders

The parotid gland

The parotid gland is the largest of the salivary glands and it is positioned anterior to the sternocleidomastoid muscle and external ear, and posterior to the masseter muscle. It extends from the zygoma down to the lower end of the mandible. It is comprised of superficial and deep lobes wrapped around the ramus of the mandible, which are separated by the facial nerve; on entering the gland, this divides into its terminal branches. Serous saliva is produced, which is stimulated by parasympathetic branches of the glossopharyngeal nerve and is secreted through the parotid duct (Stenson’s duct). This arises from the gland anteriorly crossing the masseter, piercing the buccinator muscle and opening into the oral cavity opposite the second upper molar tooth (Fig. 1) (Warner, Thirlwall, Corbridge, Patel, & Martinez-Devesa, 2009).

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Figure 1.

Location of parotid (Stenson’s duct) opening.

The submandibular gland

This gland is in the floor of the mouth and has superficial and deep parts separated by the mylohyoid. Mixed serous and mucoid saliva is produced, which is delivered into the mouth by the submandibular duct (Wharton’s duct) either side of the lingual frenulum.

The sublingual gland

The sublingual gland is oval-shaped and lies in the floor of the mouth in the sublingual fossa of the mandible. There are many small minor ducts (of Rivinus) that drain the sublingual gland; however, there is sometimes a larger main duct (of Bartholin) that opens alongside Wharton’s duct at the sublingual papillae. This gland produces mucoid saliva.

History

Taking a thorough history is the key to making a diagnosis of salivary gland pathology. The location of symptoms will help isolate the gland involved, remembering that pathology in the tail of the parotid can present with swelling in the submandibular or neck region. Salivary gland pathology can present in all age groups. Younger patients are more likely to develop viral sialadenitis, whereas tumours typically present in older patients (Mehanna, McQueen, Robinson, & Paleri, 2013).

The presence of pain is usually related to inflammatory or infective pathology. Intermittent episodes of pain associated with facial swelling are likely to be due to ductal stones or strictures. On the other hand, painless persistent swellings should prompt suspicion of a neoplastic lesion. With regards to the duration of symptoms, rapidly progressing swellings suggest salivary tumours, especially in the presence of facial nerve involvement.

Systemic symptoms may also give clues and indicate a certain pathology e.g. malaise and night sweats (lymphoma), fever (salivary gland abscess), dry eyes and dry mouth (Sjogren's syndrome) and general health (dehydration predisposes to sialadenitis).

Lastly, it is important in the history to be aware of risk factors for salivary gland cancer. These include age greater than 60 years, previous radiation exposure (i.e. radiotherapy), tobacco smoking, previous skin cancer, and family history of salivary cancer.

Examination

Start with inspection of the face, look for any obvious lumps, scars or asymmetry. As for any lump, assess the site, size, shape and skin changes such as erythema, a punctum or ulceration. Assessment of the facial nerve function is a key step; as if affected, this is more indicative of malignant pathology within the parotid gland. Assess the patient’s hydration status, as dehydration is a very common contributing factor for acute salivary gland infection.

Use a tongue depressor to inspect all aspects of the oral cavity, paying close attention to the duct openings where you may see discharging pus, calculi or obvious swelling arising from the gland. For parotid swellings it is important to inspect the oropharynx, as deep lobe pathology can present with medialisation of the pharyngeal tonsils.

Standing behind the patient, perform a full neck examination, palpating any obvious swelling of the salivary glands and along the cervical lymph node chains (Fig. 1). Examine the submandibular and parotid glands individually for enlargement, tenderness and discrete lumps. Any swelling or lump should be assessed for consistency (solid or cystic), regularity (well-defined or irregular), temperature, whether the swelling is single or multiple and fixed or mobile. Bimanual palpation of the gland and its duct is important to further assess the extent of any swelling and the presence of a ductal stone. Always compare with the contra-lateral side.

Appropriate investigations are helpful in confirming a diagnosis after a thorough history and examination is performed. These investigations are more often requested on referral to an ear nose and throat (ENT) surgeon, however, if a benign condition is suspected, they could be performed in the community prior to referral. One must remember that the suspicion of malignant disease should not result in the referral being delayed for investigations to be performed. Table 1 summarises investigations and their benefits.

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Table 1.

Investigations and their indications.

Investigations	Indications
Bloods	• Antinuclear antibody levels, rheumatoid factor and Sjogren’s antibody titres • Full blood count • C-reactive protein/erythrocyte sedimentation rate as markers of inflammation
X-ray (floor of mouth)	• Submandibular calculi are commonly radio-opaque
Ultrasound scan	• Can confirm sialadenitis/sialectasis and identify presence of salivary stone. In cases where tumour is suspected, fine needle aspiration cytology can also be performed, however, this would be arranged in secondary care
Sialogram	• Calculi, sialectasis, duct stenosis
Magnetic resonance imaging	• Neoplastic disease – especially deep lobe of parotid
Fine needle aspiration	• Investigation of neoplastic disease
Sublabial biopsy	• Confirmation of Sjogren’s syndrome

Sialadenitis

Sialadenitis refers to inflammation of a salivary gland and can be acute or chronic. There are multiple causes of sialadenitis and these can include bacterial or viral infection (e.g. mumps paramyoxovirus, see Fig. 2), radiotherapy and autoimmune pathology (e.g. Sjogren’s syndrome). Dehydration may also predispose patients to sialadenitis and will worsen sialadenitis of any cause. Any medication that decreases saliva production will also predispose patients (e.g. diuretics, anticholinergics and tricyclic antidepressants). Treatment will depend on the cause; however, all have similar symptomatic saliva-inducing measures as the mainstay of treatment (Wilson, Meier, & Ward, 2014).

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Figure 2.

Mumps.

Bacterial infections typically affect one gland, most commonly the parotid. Its classic presentation is in elderly, poorly mobile patients with poor fluid intake resulting in salivary stasis. Predisposing conditions include diabetes, hypothyroidism and Sjogren’s syndrome. Gentle massage of the affected gland may express pus from the orifice, which should be cultured, often showing Staphylococcus Aureus. Initial treatment includes oral antibiotics (e.g. Co-amoxiclav), hydration, correction of the underlying condition and stimulation of salivary flow by warm compresses and sialogogues (substances that increases saliva production e.g. vitamin C lozenges, lemon drops). If there is no clinical improvement after 24–48 hours of oral antibiotics, or suspicion of an abscess, then an immediate referral to ENT is warranted.

Viral sialadenitis is managed conservatively, as it is self-limiting and often affects the young, such as in mumps. Mumps is caused by a ribonucleic-acid-based paramyoxovirus, which can affect salivary glands, meninges and, in adults, the testes. A third problem can be subclinical infections; however, often there can be a prodrome of non-specific symptoms such as fever, malaise, myalgia, anorexia, and in some patients, parotid tenderness and swelling. Children should be excluded from school for 5 days from the onset of parotid swelling to limit transmission. Diagnosis is usually clinical; however, viral polymerase chain reaction from saliva, cerebrospinal fluid or urine can be requested. Management is mainly supportive, unless orchitis or viral meningitis develops. Similar conservative measures are used as for any cause of sialadenitis (e.g. analgesia, sialogogues, etc.). Good oral hygiene is also advised, and mouthwashes may be of use. Human immunodeficiency virus can also cause sialadenitis and should be considered in high-risk groups (Mandel, 2014).

Chronic or recurrent sialadenitis is characterised by repeated episodes of pain and inflammation caused by obstructive or non-obstructive conditions. In the former, ductal stones, strictures or scarring can impair salivary flow, resulting in recurrent inflammation. Symptoms are typically worse on eating. Non-obstructive chronic sialadenitis can be as a result of Sjogren’s syndrome or granulomatous conditions, such as sarcoidosis and tuberculosis. Primary Sjogren’s is defined as keratoconjunctivitis sicca (dry eyes) or xerostomia (dry mouth), without a connective tissue disease. In the presence of a connective tissue disease, such as rheumatoid arthritis, then it is called secondary Sjogren’s syndrome. It has a 60% association with anti-Ro antibodies, a 40% association with anti-La antibodies, and an 80% association with rheumatoid factor. Primary Sjogren’s has a 66% association with salivary gland swelling; however, this is uncommon with secondary Sjogren’s. Schirmer’s test for lacrimal secretion can be performed; however, the gold standard diagnosis is minor salivary gland (lip) biopsy. Symptoms can be managed with artificial saliva and meticulous dental hygiene, however, 5% may develop B cell lymphoma; thus, new symptoms should be investigated (Matthews, Kurien, & Scofield, 2008).

Investigations for chronic, recurring, painful swellings of salivary glands include ultrasound, and more importantly, sialography and biopsy if a systemic or granulomatous pathology is suspected. Management should be focused on identifying and addressing the underlying cause, alongside conservative measures as in acute infection. Severe cases can be safely treated by surgical excision of the affected gland.

Sialolithiasis

Calculi formation within the ductal system of a salivary gland can cause acute pain and swelling of the gland due to obstruction of salivary flow. The classic description of its occurrence is at or just before mealtimes, on anticipation of food. Eighty percent of cases affect the submandibular gland, and the parotid gland is least commonly affected. Sixty-five percent of submandibular stones are radio-opaque, thus floor-of-the-mouth X-rays can be a useful investigation tool (Warner et al., 2009). Stones are often palpable on bimanual examination, and can sometimes be expressed by this manipulation. Initial management involves hydration, massage, sialogogues and analgesia. If conservative measures fail to expel the stone, then surgical management and assessment would include a sialogram, followed by either basket endoscopic retrieval, extracorporalsialolithotripsy, intraoral incision directly over the stone or complete gland removal (Deli, Spijkervet, and Vissink, 2014).

Sialectasis

Sialectasis shows progressive destruction of the salivary gland and can be a consequence of any condition that causes chronic inflammation within the gland. Recurrent inflammatory reactions result in progressive acinar destruction with fibrosis, presenting with recurrent painful swelling, again mostly at mealtimes. It can cause strictures of the duct and salivary stones.

Pleomorphic adenoma

A pleomorphic adenoma is the most common benign tumour of the salivary glands, it tends to present as a painless enlarging smooth mass. It is often mobile and does not typically cause facial nerve palsy. It normally presents in the fifth decade of life and has a malignancy transformation rate proportional to the length of time in situ, therefore excision via superficial parotidectomy is usually performed. Surgical incision biopsy has a high risk of seeding; thus, the low-risk approach of fine needle aspiration cytology (FNAC) is the usual method of diagnosis.

Warthin’s tumour (Adenolymphoma)

This presents more commonly in males (7:1) who are in there seventh decade of life, it also has a strong association with tobacco smoking. It almost exclusively only affects the parotid gland, and 10% develop a contralateral tumour; however, it is unlikely to undergo malignant transformation. Therefore, management can include watchful waiting or surgical excision. Although it is slow-growing, it is sometimes better to remove it while it is still small, before it becomes cosmetically disfiguring and technically more difficult to remove.

Malignant tumours should always be considered if the patient has persistent symptoms and urgent referral should be made. Salivary gland malignancy accounts for between 3 and 4% of head and neck cancers (Mehanna et al., 2013). Malignancy is more likely with symptoms of facial numbness, facial nerve weakness and the presence of lymphadenopathy. A 2-week wait referral should be made, at which point initial investigation may include an ultrasound scan with FNAC and computed tomography/magnetic resonance imaging scans. The most commonly occurring histological types are mucoepidermoid carcinoma and adenoid cystic carcinoma.

Mucoepidermoid carcinoma

Mucoepidermoid carcinoma is the most common malignancy, it accounts for approximately 25% of salivary gland malignancies. Up to 90% occur in the parotid gland, and the degree of differentiation dictates the behaviour of the tumour (Warner et al., 2009). Undifferentiated tumours have a poor prognosis, due to early metastasis.

Adenoid cystic carcinoma

This is the commonest malignancy of the minor salivary glands. It tends to grow slowly along nerve sheaths, and therefore is more likely to cause facial nerve palsy. The 5-year survival rate is 80% (Cancer Research UK, 2014).

Others

Adenocarcinoma and acidic cell carcinomas are less commonly found. It is important to remember that skin cancers can present as metastatic parotid gland swellings and so thorough assessment of the scalp and face is important.