Salivary gland tumor pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Overview[edit | edit source]

The pathophysiology of salivary gland tumors depends on the histological subtype.^[1]

Pathophysiology[edit | edit source]

Pathogenesis[edit | edit source]

The parotid gland is the most frequent site of salivary gland tumors which accounts for approximately 80 to 85 percent of these tumors.^[2][3] About 75 percent of parotid lesions are benign and approximately 25 percent are malignant.^[4] 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.^[5]

• 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.^[6]

Microscopic Pathology[edit | edit source]

• Histologically, pleomorphic adenoma is the most common type of benign salivary gland tumor, which comprises about half of all salivary tumors. Other rarer benign salivary gland tumors include basal cell adenoma, Warthin's tumor, and canalicular adenoma. The most common malignant salivary gland tumors are adenoid cystic carcinoma and mucoepidermoid carcinoma, which together constitute approximately one-half of all malignant salivary gland tumors.

Histological features of benign tumors[edit | edit source]

Tabular form - adapted from Libre Pathology^[1]

Histological features of malignant tumors[edit | edit source]

Tabular form - adapted from Libre Pathology^[1]

Tumor grades of salivary gland cancer[edit | edit source]

• Grading is a way of classifying salivary cancer cells based on their appearance and behavior when viewed under a microscope. To find out the grade of a tumor, the biopsy sample is examined under a microscope. A grade is given based on how the cancer cells look and behave compared with normal cells (differentiation). This can give the healthcare team an idea of how quickly the cancer may be growing and how likely it is to spread.^[7] The grade of salivary gland cancer is based on the degree of differentiation of cells and their rate of growth.

• Grading for salivary gland cancers is used mainly for mucoepidermoid carcinomas, adenocarcinomas, adenocarcinoma NOS, squamous cell carcinomas and adenoid cystic carcinomas. Other salivary gland cancers can also be graded in the same way. Grading plays an important part in planning salivary gland cancer treatment and can also be used to help estimate the prognosis. However, the grade is not the only factor used to predict the future outcome.
• It must be considered together with staging information. Staging, in particular tumor size, is an important prognostic factor and may be more important than the grade in terms of successful treatment. For example, sometimes a stage I, intermediate or high-grade tumor can be treated with more success than a low-grade tumor that is a stage III.

• *Some adenoid cystic carcinomas can also be intermediate grade.

References[edit | edit source]

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