Epithelial-myoepithelial carcinoma arising in pleomorphic adenoma of palate

ABSTRACT

A case of epithelial-myoepithelial carcinoma transformed in pleomorphic adenoma occurring in palate of a 61 years old woman is reported. The tum or was composed of 2 different components, pleomorphic adenoma and epithelial myoepithelial carcinoma, accounting for approximately 40% and 60 % of whole tumor, respectively. As the results of the immunohistopathologic study, epithelial-myoepithelial carcinoma showed multiple tubular or solid nest, which were separated by a basement membrane and considered of variable proportion of 2 cell types, cuboidal epithelial cells positive for cytokeratin and clear myoepithelial cells positive for glial fibrillary acid protein, wheres the myoepithelial nest of pleomorphic adenoma intermingled with hyaline and myxoid stroma. The malignancy was demonstrated by convincing evidence of invasion into the submucosa, although the epithelial-myoepithelial carcinoma com ponent was mostly surrounded by the pleomorphic adenoma componemts. An increased immunoreactivity of proliferating cell nuclear antign in the epithelial myoepithelial carcinoma area in comparison to the pleomorphic adenoma also suggested epithelial-myoepithelial carcinoma arising in a pleomorphic adenoma.