Chronic parotitis is an insiduous inflammatory disorder involving the parotid gland. It is characterised by a recurrent and painful swelling of the affected salivary gland. Pain may be worse while eating due to the stress placed on the inflammed gland to secrete saliva. This condition is common in patients of middle age and is very rare in children.
It was Lilienthal in 1917 who described this entity of chronic parotitis. He called this condition as coeliac parotitis as he firmly beleived that pathology of gut somehow caused this condtion. He used a vertical incision just anterior to the auricle to drain the pus from these patients.
Other terms used to indicate this disease include:
Acute necrotizing parotitis
Acute gangrenous parotitis
Acute surgical parotitis
In 1919 British army surgeon Zachary Cope who was posted in Baghdad described chronic parotitis due to extreme dehydration in soldiers posted there. He used “T” shaped incision to drain the abscess. He was able to attribute parotitis to the extreme dehydration faced by the soldiers.
In 1923 Blair of St Louis described the external incision to drain parotid abscess.
Etiology of chronic parotitis is considered to be multifactorial. The primary pathophysiological triggering event is identified to be a decrease in the quality and quantity of salivary secretion by the involved gland. A decrease in the secretion of saliva causes stasis and inspissation of secretions causing retrograde bacterial contamination of the ductal system. If the contamination is caused by pyogenic organims then it is considered to be acute suppurative sialadenitis. These infections may result in destruction of acinar elemens and cause ductal ectasia. In advanced cases there is acinar atrophy with fibrosis which are usually accompanied by lymphocytic infiltration of the acina. Sialolithiasis may form as a result of chronic infections. It should also be borne in mind that sialolithiasis may cause chronic parotitis.
Local causes of reduced salivary flow:
Mucous plugging of the duct
Congenital abnormalities of the duct
Immune disorders like Mikulicz disease, Sjogren syndrome, chronic autoimmune parotitis
Drug induced – Atropine and antihistamines may predispose
Non obstructive causes of reduced salivary flow:
Immune mediated diseases
Infections both bacterial and viral
HIV induced parotitis:
This entity is well established and is more common in children. In children the gland is firm, non-tender and chronically enlarged. It is commonly bilateral. The course of this disorder is different in children and adults. Children with HIV induced parotitis do not suffer from xerostomia as the quantity of salivary secretion is near normal in them. Adults with HIV induced parotitis frequently present with xerostomia because of profound reduction in salivary secretion.
Histopathologic features of this unique condition include:
Follicular hyperplasia of parotid lymph nodes
Diffuse infiltration of salivary gland by CD8 T cell
Presence of benign lymphoepithelial cysts
It should be pointed out no specific therapy is available for this condition. Presence of parotitis in patients with HIV carries better prognosis.
Immune mediate parotitis:
Pathophysiology of this group of disorders is more or less similar. The initial insult to the gland is through viral infection. Peptides from these viral antigens and autoantigens gets associated with class II histocompatibility molecules in the cytoplasm of the epithelial cells. These HLA complex gets expressed on the cell surface. The CD4 T cells recognize these antigens and promote immune reaction by releasing a series of cytokines.
Painful swelling of the gland associated with fever – Bacterial parotitis
Bilateral swelling of parotid gland associated with mild fever (children) – Viral parotitis (Mumps). The whole symptoms lasts for a period of less than a week. Self limiting disorder.
Non painful asymptomatic glandular enlargement – HIV parotitis
Recurrent chronic swelling of one / both parotid glands with associated complaints of dry mouth and eyes – Sjogren's syndrome
Parotid gland is enlarged.
May be tender / non tender
Skin over the swelling may be inflammed
Fluctuant in cases of purulent parotitis
Massaging the gland from posterior – anterior direction will cause saliva to the extruded from the parotid duct in normal glands. Pus can be seen extruding if the gland is suppurative.
Sialography: Sialography performed by injecting contrast agent into the ductal system of the salivary gland has been the technique followed to assess the ductal system for many years. The ductal dilatation and acinar distortion are readily appreciated in a sialogram.
The changes appreciated by studying a sialogram have been classified into four types:
Type I: In this type of sialogram there is mild irregular dilatation of the main duct. Interlobar and interlobular acini are not involved.
Type II: In this type the anterior part of the main duct is normal, while its posterior portion is irregularly dilated. This feature is seen in punctate sialectasis which is a feature of autoimmune parotitis.
Type III: The whole main duct is irregularly dilated. This dilatation also extends to the branching ducts also.
Type IV: This is the most severe change demonstrated in a sialogram. There is irregular dilatation of the main duct as well as the branching ducts. There is also associated acinar atrophy.
Conservative management include:
Antibiotics – sinc staph aureus is the commonest pathogen a penicillinase resistant penicillin or a first generation cephalosporin is preferable.
Salivary gland massage
Methyl violet injection into the duct: This method has been popular in China since 1980. These patients were treated with injections of 1% methylviolet into the duct. Patients respond well to this management modality with no incidence of recurrence.
Surgical drainage of acute abscess:
Acute suppurative abscess involving the parotid gland should be drained. The major draw back of surgical drainage is the possible development of salivary cutaneous fistula. If incision is sited as shown in the figure the incidence of salivary fistula is rather low.
Figure showing incision to drain parotid abscess