Myoepithelioma presenting as a midline cystic tongue lesion: cytology, histology, ancillary studies, and differential diagnosis.

Salivary gland myoepithelioma (ME) is a neoplasm derived from myoepithelial cells that lacks the ductal and broad mesenchymal differentiation seen in the vast majority of mixed tumors. This report describes the cytologic findings of a cystic ME presenting in the midline of the dorsal tongue, a site where no salivary glands are generally present. The tumor was well circumscribed and composed of sheets of monotonous epithelioid cells without ductal cells. The cells were positive for S-100 protein and ultrastructurally had features of myoepithelial cells. The fine needle aspiration (FNA) biopsy findings, differential diagnosis, histology, immunohistochemistry, and electron microscopic features of this interesting and uncommon neoplasm are presented. To the best of our knowledge, there have been no cytologic reports of ME of the tongue.