EPITHELIAL-MYOEPITHELIAL CARCINOMA OF THE SALIVARY-GLANDS - A REVIEW OF LITERATURE

Epithelial-myoepithelial carcinoma (EMC) of the salivary glands is a r are tumor first described by Donath et al in 1972 and recognized as a distinct pathologic entity in the 1991 WHO classification. The EMC com prises approximately 1% of all salivary gland tumors. The histological hallmark is a biphasic cell arrangement formed by an inner layer of d uct-forming epithelial cells and an outer layer of myoepithelial cells . The epithelial-myoepithelial dualism is confirmed using immunohistoc hemical methods: the epithelial cells are immunoreactive for low molec ular weight keratin; the myoepithelial cells are immunoreactive for S- 100 protein, muscle specific actin and vimentin. Most reported follow- up information indicates that EMC is a low-grade malignant tumor; howe ver, from the analysis of the various series it is demonstrated that t umors with a solid growing pattern, nuclear atypia, DNA aneuploidy and high proliferative activity, generally have a more aggressive behavio r and a higher frequency of local recurrences and metastases.