Sarcoidosis of the Salivary Gland

Definition

Sarcoidosis is a chronic inflammatory condition of unknown origin, which may involve salivary glands. It has some characteristic clinical features and histological findings but in essence is a diagnosis of exclusion.

Incidence/Age

A rare condition found mostly in adults, with only occasional cases described in children. Clinically, salivary gland involvement occurs in 6% of cases, but 33% of patients are said to have some histological involvement. It is most common in the 30-40 year old age group.

Anatomy & Physiology

The parotid gland consists of a superficial (outer) and a deep (inner) part, which are separated by the tree-like terminal branches of the facial nerve, responsible for facial movement. Lymph nodes are present within the gland.

Saliva leaves the gland through Stensen's duct, which pierces the facial muscles and enters the mouth through the cheek opposite the second upper molar tooth. Saliva flow is stimulated by chewing and the presence of food in the mouth, particularly sour substances. The stimulus is mediated via parasympathetic nerve fibres carried on the auriculotemporal nerve to the parotid gland.

The submandibular gland consists of superficial and deep parts separated by the myelohyoid muscle. The duct leaves the deep part of the gland and enters the floor of the mouth, meeting its opposite partner. The deep part of the gland is intimately related to the hypoglossal nerve, which moves the tongue, and the lingual nerve, which provides sensation to the front half of the tongue.

Saliva flow is stimulated by the parasympathetic (chorda tympani) nerve fibres, carried along the lingual nerve.

Causes

The cause is unknown.

Symptoms/Signs

Swelling of some or all salivary glands, as well as tear glands, causing dry mouth and dry eyes. Sarcoidosis is the commonest cause of bilateral parotid swelling. Salivary gland swelling may last for months or years but eventually resolves spontaneously.

Complications of Disorder

• Uveoparotid fever (Heerfordt's disease), a flu-like illness preceeding salivary swelling lasting for days to several weeks. It may also be associated inflammation of the eyes (uveitis). This may occur with or without systemic manifestations of sarcoid.
• Transient facial palsy.
• Uveitis may progress to glaucoma.

Tests

• Chest X-ray to look for features of systemic sarcoid.
• Minor salivary gland biopsy from the lip or palate this can be done under local anaesthetic.
• Kweim test. This involves injecting material isolated from guinea pigs suffering from sarcoidosis under human skin and identifying a typical skin response, which can then be biopsied to identify characteristic non-caesiating granulomata.

Treatment

Medical

There are no specific medical treatments and symptoms eventually resolve spontaneously. Complications in particular facial palsy is said to respond more rapidly if oral steroids are given.

Surgical

There is no active role for surgical treatment except in providing tissue for histological diagnosis.

Outcome/Prognosis

Usually good with complete resolution of symptoms over time.

Recommended Further Reading

Head & Neck Surgery - Otolaryngology, edited by Byron J. Bailey, second edition, Vol. 1, chap 37. Diseases of the Salivary glands non neoplastic by Dale H. Rice p475- 483.