The basics - Assessing parotid swellings

There are many possible causes of parotid swellings, from Sjogren's syndrome to either benign or malignant neoplasms, explain Mr Malcolm Buchanan, Dr Himat Thandi and Miss Jaan Panesar.

Pleomorphic adenoma of the parotid at the angle of mandible
Pleomorphic adenoma of the parotid at the angle of mandible

The rate of growth of a parotid swelling, whether or not it is painful, and the presence of any associated symptoms such as xerostomia and xerophthalmia that might suggest Sjogren's syndrome, can all be established from a good history.

Facial weakness and rapid growth are indicative of malignancy, where pain is not usually a presenting feature. Sudden swelling, especially if painful, suggests obstruction, inflammation or infection.

Intermittent swelling occurring with eating or drinking implies parotid (Stensen's) duct obstruction, and if painful could indicate a parotid calculus. However, parotid calculi are rare, but may occur in hyperparathyroidism.

The patient should be asked if swelling ever involves both parotid glands. Bilateral involvement suggests a metabolic aetiology (such as diabetes, sarcoidosis, anorexia, bulimia or Sjogren's syndrome) or an infective cause, including mumps, cytomegalovirus and HIV.

It is also important to know whether or not the patient has had previous parotid surgery for a neoplasm, and if so, whether this lump is a recurrence.

Anatomy and examination
The parotid gland extends superiorly from the level of the temporomandibular joint to behind the ramus of the mandible inferiorly, and anteriorly as far as the insertion of the masseter muscle into the zygoma.

The site and size of lump should be noted, including the presence of overlying skin changes such as erythema or ulceration, or a scar from previous tumour surgery. Palpation determines the size, consistency, fluctuance and tenderness of the lump.

Movement of the skin over the lump should be checked to exclude an intradermal lesion. If the lump is within the parotid, skin movement should be possible, unless infiltrated by malignancy. Tumours are usually discrete lumps within the parotid, whereas infection and calculi result in diffuse, tender enlargement of the gland.

The facial nerve bisects the parotid into superficial and deep lobes. Malignant parotid lumps can invade the facial nerve, resulting in paresis, so facial nerve function should be assessed.

Malignant lumps are usually non-tender, but may involve the skin, resulting in fixation and even ulceration or fungation.

Palpation of the neck may detect metastatic spread or reactive cervical lymphadenopathy. A tumour of the parotid tail can sometimes be mistaken for a level II (upper cervical) lymph node, and vice-versa. Squamous cell carcinomas and malignant melanomas of the head and neck can metastasise to the parotid, so an examination of the pinnae, face and scalp is essential.

About 10 per cent of parotid neoplasms are deep lobe tumours and involve the parapharyngeal space, lateral to the tonsil. The oropharynx should therefore be examined for peritonsillar or soft palate swelling.

Eighty per cent of parotid tumours are benign, the most common being pleomorphic salivary adenomas. These grow exponentially, and - if long-standing - can predispose to carcinoma.

Benign parotid lumps are typically firm and non-tender, with no associated skin changes.

Adenolymphomas, or Warthin's tumours, typically occur in smokers and in the elderly. They remain benign, feel cystic, and are bilateral in 10 per cent of cases. They are usually managed conservatively.

Key points
  • Determine rate of growth from the history.
  • Fixation to skin or facial nerve involvement suggest malignancy.
  • The oropharynx should be examined for peritonsillar or soft palate swelling.
  • Granulomatous conditions can present with firm, non-tender swellings of both parotid and submandibular glands.

 

Inflammation and infection
Inflammatory conditions of the parotid, such as acute suppurative bacterial parotitis, can present as a diffuse, tender enlargement of the gland.

Predisposing factors include dehydration, underlying tumour, parotid calculus or decreased salivary flow from previous radiotherapy.

The parotid papilla (opposite the second upper molar) may appear oedematous, and exudation of pus from the parotid duct may be seen if the gland is compressed. Intra-oral palpation of the duct orifice rarely reveals calculi. Bilateral parotitis, especially in children, suggests mumps.

Granulomatous conditions such as TB, sarcoidosis, syphilis, Wegener's granulomatosis and cat scratch disease, can present with firm, non-tender swellings of both the parotid and submandibular glands.

Autoimmune lymphocytic infiltration of the parotid gland and other salivary tissues, in conjunction with xerostomia and xerophthalmia, encompasses primary Sjogren's syndrome, and is more common in females.

Where there is a co-existing connective tissue disorder, such as rheumatoid arthritis, the condition is termed secondary Sjogren's syndrome.

Management of swellings
Treat acute suppurative parotitis with oral flucloxacillin and metronidazole, stimulate saliva flow with sialagogues such as citric fruits, and encourage adequate hydration.

Patients who do not improve on oral antibiotics should be admitted to hospital for IV antibiotics and rehydration. Mumps parotitis can generally be treated symptomatically.

Uncomplicated sialolithiasis should be treated initially by stimulating saliva flow and massaging the gland. Failure to improve warrants referral for radiological assessment for the presence of a stone.

Non-infectious and non-inflammatory parotid lumps should be referred immediately to an ENT clinic for cytological assessment. If Sjogren's syndrome is suspected, Ro (SSA) and La (SSB) autoantibody levels may be measured to help confirm the diagnosis.

Xerostomia and xerophthalmia can be treated with saliva substitutes and artificial tears.

Chronic metabolic causes of parotid enlargement should be referred for cytology, and a labial biopsy performed to diagnose Sjogren's syndrome.

  • Mr Buchanan is a specialist registrar and Miss Panesar is a consultant otorhinolaryngologist at the department of otolaryngology, Luton and Dunstable Hospital, and Dr Thandi is a GP in Bradford

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