Fine needle aspiration cytology of epithelial-myoepithelial carcinoma of salivary glands - A report of three cases

BACKGROUND: Epithelial-myoepithelial carcinoma is a rare, low grade maligna nt tumor of the salivary glands. Histologically, if has a biphasic cellular composition and exhibits a high degree of differentiation. The fine needle aspiration cytology of this rare tumor is rarely described in the literatu re. CASES: We report the fine needle aspiration cytology of three epithelial-my oepithelial carcinomas, arising in the right parotid, left parotid and mino r salivary gland of the hard palate. Cytology showed a biphasic population consisting of cells of ductal epithelial and myoepithelial origin arranged in small clusters and sheets. The myoepithelial cells had small, uniform nu clei; ample, clear cytoplasm and distinct cell borders, while the ductal ep ithelial cells had larger, mildly pleomorphic nuclei and scanty cytoplasm. These ductal cells tended to form tubules among background sheets of clear myoepithelial cells. This feature, if present, was an important diagnostic clue. Hyaline material surrounding cell clusters and focal adenoid cystic c arcinoma-like areas with orangeophilic globules were also not uncommon. CONCLUSION: While the cytologic appearance of epithelial-myoepithelial carc inoma may closely mimic that of other salivary gland tumors, such as adenoi d cystic carcinoma, pleomorphic adenoma and basal cell adenoma, certain pec uliar cytologic features may allow a distinction to be made on fine needle aspiration biopsy.