Most surgical pathology of the salivary gland presents as a swelling in the associated gland and it is helpful clinically to characterise the swelling as one that affects the whole of the gland or as a discrete swelling that affects only part of the gland. Most discrete swellings are caused by a tumour, whereas swellings affecting the whole of the gland are usually caused by sialolithiasis, sialadenitis or sialadenosis (Table 14.1). There is obviously some overlap in this classification but it is helpful in the clinical context.
Table 14.1 Salivary gland swellings
Discrete tumours Diffuse sialolithiasis sialadenitis sialadenosis
Sialolithiasis, or salivary gland stone disease, is caused by the presence of stones either within the gland itself or in the duct that is draining the gland, symptoms being more common when the stones are found in the ducts. The presentation and diagnosis of these are considered in detail in Chapter 34.
Stones in the anterior part of the submandibular duct can be removed via the mouth by opening (and marsupialising) the duct (see Ch. 34) but if the stone is further back in the duct, or in the submandibular gland itself, then it is safer to remove the gland externally by a neck incision to avoid damage to the lingual nerve. Recurrent parotid duct stones are rare and if they cannot be removed through the mouth and are considered very troublesome then they require a parotidectomy, but this is very unusual. Dilatation of the parotid duct has been tried for parotid duct stones, especially when they are associated with a stricture in the parotid duct, and this is worth trying as it is a lot less invasive and has lower morbidity than a parotidectomy, but its effectiveness is doubtful.
Sialadenosis is defined as a non-inflammatory salivary gland disease due to metabolic and secretory disorders of the gland parenchyma, accompanied by recurrent, usually painless, bilateral swelling of the glands due to acinar enlargement.
Sialadenosis has an equal incidence in the two sexes and occurs most commonly in the fourth to seventh decades. The disease is suspected when there is recurrent enlargement of both pairs of the major salivary glands, usually the parotids (Fig. 14.9). The gland enlargement can persist from weeks to months. It is usually associated with an underlying condition. Sialadenosis has three major causes:
Fig. 14.9 Sialosis occurring in a patient with a history of alcohol abuse.
Fig. 14.9 Sialosis occurring in a patient with a history of alcohol abuse.
• Endocrine: gland enlargement has been described in most endocrine diseases but it is particularly linked to diabetes mellitis. It can also occur during pregnancy and lactation where its cause is thought to be endocrine in origin.
• Dystrophic/metabolic: this is most commonly seen in chronic starvation and is thought to be linked to the deficiency of proteins and vitamins. This is also the reason it is sometimes seen in alcoholics.
• Neurogenic: dysfunction of the autonomic nervous system can give rise to sialadenosis and this is most commonly seen in people taking drugs that affect the autonomic nervous system, such as some antihypertensive drugs, It may also be the reason it is seen in patients who are anorexic but there is probably also a nutritional element in this as well.
The diagnosis is made upon the history and clinical appearance associated with an underlying cause. A parotid biopsy is needed occasionally, and histology will then show acinar enlargement.
The underlying disease is treated but it is very rare that a parotidectomy will be needed for cosmetic reasons. Even with treatment of the underlying disease, it is common for the parotid enlargement to persist.
Sialadenitis is inflammation of the salivary glands, most commonly the parotid, and can be categorised into acute and chronic types (Table 14.2).
Acute sialadenitis may be bacterial or viral in nature. Viral sialadenitis is self-limiting and only bacterial sialadenitis will be considered here.
Bacterial infection usually presents with a sudden sense of swelling of the affected gland and there may be redness of the overlying skin. Pus is often seen exuding from the salivary gland duct into the mouth and the patient is unwell. Most acute bacterial infection is related to a reduction in the flow of saliva and this is commonly secondary to an underlying disease such as poorly controlled diabetes mellitis or renal failure and occurs in older patients. There is often an association with poor oral hygiene. It used to be a common postoperative finding but now, with the use of antibiotics and better fluid management and postoperative oral toilet, it has become an uncommon disease.
Treatment is usually with antibiotics and correction of the underlying disease processes if present. Sialogogues (e.g. citrus-flavoured sweets) are often given to encourage the flow of saliva. If an abscess develops it may need draining externally. Care must be taken not to damage the facial nerve when the parotid gland is affected.
Chronic sialadenitis has several causes (see Table 14.2) and usually presents with persistent inflammation and enlargement of the affected gland.
This presents mainly as a unilateral or alternating swelling of the parotid gland, which can be painful. It is mainly a disease of children and the saliva can be very milky or purulent. Attacks occur at variable intervals and in between attacks the child is totally symptom free. The underlying cause is not known but it is thought that duct ectasia may be a predisposing factor.
Diagnosis is again made from the history and sialography can be considered. Duct ectasia supports the diagnosis when seen on sialography.
Treatment is symptomatic as the underlying cause is not fully understood. It often involves antibiotics and analgesia and sialogogues are often given. Most cases in childhood disappear after puberty. If the attacks continue, ligation of the parotid duct or a tympanic neuroectomy can be recommended. It is very occasionally necessary to perform a parotidectomy.
Tuberculosis can present as a chronic sialadenitis, affecting mainly the parotid or submandibular gland. Its diagnosis may not be suspected if the patient is not known to have tuberculosis and is often diagnosed by biopsy when the cause of a unilateral parotid gland enlargement remains obscure. Occasionally the disease can cause a fistula to develop into the skin above the parotid and this is strongly suggestive of tuberculosis.
The salivary glands are very sensitive to the effects of radiation and this is especially a common problem in patients who have been irradiated for head and neck cancer, as the major and minor salivary glands are often included within the field. They present with a dry mouth and the presence of thick tenacious saliva, which can be very distressing. Unfortunately the symptoms tend not to improve with time.
Treatment is symptomatic and although many types of artificial saliva are available on the market, their clinical effectiveness is not high.
A consideration of Sjogren's syndrome is beyond the scope of this chapter. The significance of Sjogren's syndrome to surgical practice is that there is an increased incidence of malignancy associated with this condition, especially non-Hodgkin's lymphoma. If there is an associated parotid swelling with Sjogren's syndrome then there is a 70-fold increase in the development of a non-Hodgkin's lymphoma. In patients with no salivary gland swelling this decreases to a 10-fold increase in incidence of non-Hodgkin's lymphoma and these patients should therefore be followed-up to watch for this.
There is no specific treatment for Sjogren's syndrome apart from symptomatic treatment and treatment of the underlying connective tissue disease present. A rapidly enlarging salivary gland should be biopsied to rule-out a lymphoma.
Sarcoidosis can effect the salivary glands, especially the parotid glands, causing them to enlarge. Treatment is usually with corticosteroids.
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