Abstract

Malignant myoepithelioma is a rare neoplasm of salivary gland which may either arise de novo or develop in a pre-existing pleomorphic adenoma. The malignant myoepithelioma occurs in 0.45% of major salivary gland tumors. Malignant myoepitheliomas arising in the pleomorphic adenoma number less than 20 in English literature and 1 in Korea. We describe a case of malignant myoepithelioma arising in a recurrent pleomorphic adenoma of the left parotid gland of a 61-year-old man. The tumor was ill-defined and composed of polygonal or plasmacytoid myoepithelial cells. Infiltration to surrounding tissue, hemorrhage, necrosis, increased mitotic activity and vascular tumor emboli indicated its malignant nature. There were several satellite nodules with histologic features of typical pleomorphic adenoma. Immunohistochemically, tumor cells were reactive for S-100 protein, AE1/AE3, vimentin, smooth muscle actin and glial fibrillary acid protein.

• Keywords: Malignant myoepithelioma;Pleomorphic adenoma;Parotid gland