Salivary gland tumors

	Salivary gland tumors Microchapters
Patient Information
Overview
Pathophysiology
Classification

For detailed chapter of salivary gland tumors click here

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]

Synonyms and keywords: salivary gland cancer; salivary gland neoplasia; salivary gland neoplasm; parotid tumor; parotid cancer; parotid neoplasia; parotid neoplasm; parotid gland tumor; parotid gland cancer; parotid gland neoplasia; parotid gland neoplasm; submandibular tumor, submandibular cancer; submandibular neoplasia; submandibular neoplasm; submandibular gland tumor; submandibular gland cancer; submandibular gland neoplasia; submandibular gland neoplasm; sublingual tumor; sublingual cancer; sublingual neoplasia; sublingual neoplasm; sublingual gland tumor; sublingual gland cancer; sublingual gland neoplasia; sublingual gland neoplasm; minor salivary gland cancer; minor salivary gland neoplasia; minor salivary gland neoplasm

Overview

Salivary gland tumor is a tumor that forms in the tissues of a salivary gland. The salivary glands are classified as major and minor. The major salivary glands consist of the parotid, submandibular, and sublingual glands. The minor glands include small mucus-secreting glands located throughout the palate, nasal, and oral cavity. Malignant salivary gland neoplasms account for approximately 0.5% of all malignancies and approximately 3% to 5% of all head and neck tumors. Salivary gland tumors may be classified according to the World Health Organization into five groups: malignant epithelial tumors, benign epithelial tumors, soft tissue tumors, hematolymphoid tumors, and secondary tumors. The pathophysiology of salivary gland tumors depends on the histological subtype. There are no established causes of salivary gland tumors. The incidence of salivary gland tumors is approximately 2.5 to 3.0 individuals per 100,000 individuals worldwide. The incidence of salivary gland tumors is estimated to be 2000 to 2500 cases per year in the United States. The incidence of salivary gland tumors increases with age; the median age at diagnosis is 64 years. Salivary gland tumors are more common in males than females. There is no racial predilection to the salivary gland tumors. Common risk factors in the development of salivary gland tumors are age, radiation exposure, environment and occupational exposure, certain viruses, male gender, smoking, and family history. Symptoms of salivary gland tumor includes difficulty swallowing, muscle weakness on one side of the face, a lump or swelling on or near the jaw or in the neck or mouth, numbness in part of the face, persistent pain in the area of a salivary gland, and trouble opening the mouth widely. The optimal therapy for salivary gland tumors depends on the stage at diagnosis. The mainstay of therapy for salivary gland tumors is surgery. External beam radiation therapy may be used following surgery, when surgery is not possible, or would cause significant complications. Chemotherapy is considered when radiation therapy or surgery is not possible.

Pathophyisiology

The parotid gland is the most frequent site of salivary gland tumors which accounts for approximately 80 to 85 percent of these tumors.^[1]^[2]
About 75 percent of parotid lesions are benign and approximately 25 percent are malignant.^[3]
Less frequently, salivary gland tumors originate in the sublingual, submandibular, and minor salivary glands, which are located throughout the submucosa of the upper aerodigestive tract and mouth.^[4]

In comparison to tumors arising in the parotid, 70 to 90 percent of sublingual gland tumors, 50 to 75 percent of minor salivary gland tumors, and 40 to 45 percent of submandibular gland tumors are malignant.
Approximately 85% of salivary gland tumors occur in the parotid glands, followed by the minor salivary glands and submandibular, and approximately 1% occur in the sublingual glands.
Overall approximately 80% of all parotid masses are benign.^[5]

Classification

Due to diverse nature of salivary gland neoplasms, many different terms and classification systems have been used. The World Health Organization in 2004, classified salivary neoplasms as primary or secondary, benign or malignant, and also by tissue of origin. This system defines five broad categories of salivary gland neoplasms: