Parotid Gland - Pathology

Pathology

Inflammation of one or both parotid glands is known as parotitis. The most common cause of parotitis is mumps. Widespread vaccination against mumps has markedly reduced the incidence of mumps parotitis. Other infections such as bacterial infections can cause parotitis as may blockage of the duct, whether from salivary duct calculi or external compression. Stones mainly occur within the main confluence of the ducts and within the main parotid duct. The patient usually complains of intense pain when salivating and tends to avoid foods which produce this symptom. In addition, the parotid gland may become enlarged upon trying to eat. The pain can be reproduced in clinic by squirting lemon juice into the patient's mouth. Surgery depends upon the site of the stone: if within the anterior aspect of the duct a simple incision into the buccal mucosa with sphinterotomy may allow removal; however, if situated more posteriorly within the main duct, complete gland excision may be necessary.

Swelling of the parotid gland may also indicate the eating disorder bulimia nervosa, creating the look of a heavy jaw line.

Eighty to eighty-five percent of tumors of the parotid gland are benign. The most common of these include pleomorphic adenoma (70% of tumors, affecting predominantly females (60%)) and Warthin's tumor. Their importance is in relation to their anatomical position and tendency to grow over time. The tumorous growth can also change the consistency of the gland and cause facial pain on the involved side since the facial nerve travels through the gland.

Fifteen to twenty percent of parotid tumors are malignant with the most common tumors being mucoepidermoid carcinoma and adenoid cystic carcinoma. Critically, the relationship of the tumor to the branches of the facial nerve (CN VII) must be defined because resection may damage the nerves, resulting in paralysis of the muscles of facial expression.

Surgical treatment of parotid gland tumors is sometimes difficult, on the one hand because of the anatomical relations of the facial nerve parotid lodge, but also through the increased potential for postoperative relapse. Thus, detection of early stages of a parotid tumor is extremely important in terms of postoperative prognosis.

Operative technique is laborious, because of relapses and incomplete previous treatment made in other border specialties.