[An epithelial myoepithelial carcinoma of the parotid gland]

A case of epithelial myoepithelial carcinoma is reported. Histologically, this tumor shows tubular and solid growth pattern. The inner layer of the tubules is composed of cells with an eosinophilic cytoplasm that is surrounded by cells with clear cytoplasms. Clear cells also manifest a solid growth pattern. Immunohistochemical and electron microscopic examinations has revealed that the cells with an eosinophilic cytoplasm have the characteristics of the ductal epithelium and that the clear cells have the characteristics of the myoepithelium. Immunohistochemically, keratin positive clear cells and S-100 protein positive ductal cells were found in our case. This suggests the existence of cells having both ductal and myoepithelial characteristics and this inspected tumor had derived from multipotential cells of intercalated ducts.