Myoepithelioma of salivary glands: report of 23 cases.

Twenty-three neoplasms arising in major and minor salivary glands have been found to be composed of two types of myoepithelial cells--the plasmacytoid and spindle-cell form. Twelve of these were located within the parotid gland and the submandibular gland and intraoral minor salivary glands accounted for five each. A solitary example was found within the upper lip. Sixteen (70%) of the cases were of the spindle-cell type, four (17%) were composed of plasmacytoid cells, and three cases (13%) contained both cell forms in approximately equal quantity. Differences in behavior, recurrence rate, frequency, age of the patient, and location were not related to cell type. Ultrastructural analysis of selected cases showed myofilament aggregation patterns to vary between the two subtypes. Previously published cases confirmed by electron microscopy have been reviewed and compared with the 23 cases reported. Conservative surgical management is curative. Follow-up information on 16 cases is presented.