Myoepithelima of the parotid gland initially diagnosed by fine needle aspiration cytology and immunocytochemistry - A case report

Background Myoepithelioma is a rare, benign tumor of the salivary gland, most commonly affecting the parotid gland. Although the cytologic features of myoepitbelioma are documented, it has rarely been diagnosed mented in a few case reports, it has been diagnosed preoperatively by fine needle aspiration (FNA) cytology. Case A 33-year old man presented with a left parotoid-swelling 2.5 cm in diameter and of about 5 years' duration. FNA smears showed hundles of spindle-shaped cells as well as plasmacytoid and stellate cells in sheets and dissociated forms. A few cells bad unclear grooves, and occasional cells showed intranuclear cytoplasmic inclusions. In May-Grunwald-Giemsa-stained smears, most of the cells had reddish cyto-plasm. Red to purple, myxoid matrix was present as a scan l fibrillar substance and as globules surrounded by tumor cells vaguely reminiscent of adenoid cystic carcinoma. A cytodiagnosis of myoepithelioma was given and corroborated by immunocytochemical staining, which revealed a positive reaction for vimentin, smooth muscle actin and S-100 protein. Epithelial membrane antigen yielded a negative reaction on except for a few plasmacytoid cells with weakly positive staining. Histopathology of the resected tumor and immunohistochemical staining confirmed the cytodiagnosis of myoepithelioma. Conclusion FNA cytologic features together with immunocytochemical studies on smears can offer a preoperative diagnosis of myoepithelioma.