This uncommon tumor is composed of malignant myoepithelial cells arranged in an infiltrative growing pattern and showing high mitotic activity. The cytology is that of a highly malignant tumor, the cells are rounded or elongated, marked nuclear atypia is present. Many bare atypical nuclei are usually visible. In some occasion cytoplasmic vacuolization, nuclear and cytoplasmic inclusions are found. Myoepithelial adenomas may undergo malignant transformation, recurring tumors of a previous removal of a myoepithelial tumor may develop continuously more and more aggressive cytology picture.