Abstract
Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland neoplasm, pathologically characterized by a bilayer structure composed of clear myoepithelial cells that surround duct lining cells. This case report describes EMC of the deep lobe of the parotid gland.
The patient was a man in his sixties who had been aware of a left preauricular mass for one year, and was referred to our department. An elastic and slightly-hard mass in the left preauricular region, measuring 2.6 × 2.0 cm, was recognized. There was no facial nerve palsy and no palpable cervical lymph adenopathy. Ultrasonographic examination and magnetic resonance imaging showed a well-defined border mass with internal heterogeneity in the left parotid gland.
Based on the clinical diagnosis of tumor of the left parotid gland, excision of the tumor was performed while preserving the facial nerve. Histopathological examination revealed a biphasic cellular composition of inner layer cells with eosinophilic cytoplasm and outer layer cells with clear cytoplasm. Immunohistochemically, the inner cells were stained with cytokeratin (AE1/AE3) and the outer cells were stained with α-SMA and S-100. The tumor was diagnosed as EMC. Since extracapsular tumor invasion was observed in some part, postoperative radiotherapy of 46 Gy was administered. He has no evidence of disease 3 years after surgery.
