Tumors of the minor salivary glands: A study of twenty-three cases

Abstract

One hundred eighty-one previously reported cases of minor salivary gland tumors have been reviewed, and twenty-three additional cases of these tumors have been described. These new cases fell into the following groups: pleomorphic adenomas (4), canalicular adenomas (4), myoepitheliomas (3), mucocyst adenoma (1), fibroadenomas (3), mucoepidermoid tumors (6), and adenocarcinomas (2). Various special stains were used to demonstrate the cellular elements of these tumors. Mucicarmine stain demonstrated that the so-called “pseudocartilage” of the pleomorphic adenomas is a result of admixture of mucin and stromal materials into which the parenchymal cells are incorporated. Relatively rare canalicular adenomas and myoepitheliomas are described. These tumors consist almost exclusively of ductal cells and myoepithelium, respectively. A benign tumor of unusual morphology is described for the first time. It consisted of sheets of an eosinophilic polygonal cell with interspersed pools of mucin. This neoplasm was termed mucocystadenoma . Since, from the microscopic picture alone, the innocence or the malignancy of mucoepidermoid tumors cannot be established, these tumors were not subdivided into the malignant and benign varieties. It is suggested that all mucoepidermoid tumors be considered malignant or potentially malignant. The most common site of origin of the tumors of minor salivary glands was found to be the palate, and the most common neoplasm was the mucoepidermoid tumor. This is in contrast to the tumors of the major salivary glands, the majority of which are pleomorphic adenomas of the parotid gland. Because of their size and location, most of the reported tumors of the minor salivary glands were clinically misdiagnosed as mucoceles or fibromas.