Excerpt from Salivary Gland Tumors, Minor, Benign

Synonyms, Key Words, and Related Terms: SGT, benign tumors of the minor salivary glands, benign epithelial tumors, pleomorphic adenoma, Warthin tumor, monomorphic adenoma, intraductal papilloma, oncocytoma, sebaceous neoplasms, cystadenoma lymphomatosum, cystic papillary adenoma, adenolymphoma, lymphoepithelial hyperplasia, Mikulicz disease, intraductal papilloma, papillary cystadenoma, oxyphil adenoma, oncocytoma, benign nonepithelial tumors, lipoma, hemangioma, angioma, lymphangioma, cystic hygroma, neural sheath tumors, melanoma, squamous cell carcinoma, salivary gland neoplasm, minor salivary gland resection, parotidectomy, intraoral resection, mandibulotomy, submandibular gland surgery

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Tumors of the salivary glands are uncommon and represent 2-4% of head and neck neoplasms. They may be broadly categorized into benign neoplasms, tumorlike conditions, and malignant neoplasms. The glands are divided into major and minor salivary gland categories. The major salivary glands are the parotid, the submandibular, and the sublingual glands. The minor glands are dispersed throughout the upper aerodigestive submucosa (ie, palate, lip, pharynx, nasopharynx, larynx, parapharyngeal space).

Most (70%) salivary gland tumors (SGTs) originate in the parotid gland. The remaining tumors arise in the submandibular gland (8%) and minor salivary glands (22%). Although 75% of parotid gland tumors are benign, slightly more than 50% of tumors of the submandibular gland and 60-80% of minor SGTs are found to be malignant. Pleomorphic adenomas (benign mixed tumors) are the most common benign SGTs, comprising 85% of all salivary gland neoplasms.

The ubiquitous deposition of the minor salivary glands complicates the diagnosis and management of SGTs. The approach for a suspected tumor of the minor salivary glands begins with a thorough history and a physical examination. Radiographic imaging (CT with or without MRI) and a histopathologic diagnosis (obtained based on fine needle aspiration biopsy [FNAB]) often provide useful information prior to definitive surgical therapy.

History of the Procedure: Salivary gland surgery dates back to the 16th century. The anatomy of the parotid gland and the role of the main ducts were described in the mid-17th century. The earliest references to "para-auricular swellings," as the Greeks called them, described the findings associated with calculi and inflammation.

Between 1650 and 1750, salivary gland surgery was limited to the treatment of ranulas and oral calculi. The concept of surgical excision of a parotid tumor has been attributed to Bertrandi in 1802. The initial applications of this surgery included an extensive approach, causing serious disfiguration and disability.

In about the 1850s, the focus shifted toward dissection and the intimate relationship between the facial nerve and the parotid gland. Attempts were made to perform the surgery with nerve preservation. John C. Warren, MD, was the first to use ether inhalation anesthesia during his resection of a parotid tumor in Boston in 1846. In 1892, Codreanu (a Romanian native) performed the first total parotidectomy with facial nerve preservation. Grafting of the facial nerve after resection was attempted in the early 1950s.

Beahrs and Adson (1958) eloquently described the relevant anatomy and surgical technique of current parotid gland surgery. They stressed surgical landmarks for avoiding injury to the facial nerve and advocated complete removal of the superficial portion of the parotid gland for noninvasive lesions confined to that portion of the gland.

Problem: SGTs usually manifest as an enlargement of the salivary glands.

Investigate weight loss, underlying infectious processes (eg, chest pain, cough, lymphadenopathy), and clinical indications of lymphoma–type B symptoms (eg, night sweats, fever).

Frequency: Tumors of the parotid gland are the most common SGTs and are 5 times more common than tumors of the minor salivary glands. The latter are almost twice as common as neoplasms that develop in the submandibular gland. The incidence of salivary gland neoplasms peaks in the fifth decade of life. The most common benign tumor is the benign mixed tumor, or pleomorphic adenoma.

Sixty to eighty percent of all minor SGTs are malignant. Overall, adenoid cystic carcinoma is the most common malignant tumor of all minor salivary glands. The submandibular gland has a high incidence of malignant tumors (65% malignant vs 35% benign).

Etiology: Although the etiology of SGTs is unknown, the involvement of environmental or genet .....