Myoepithelial cells: Current perspectives in salivary gland tumors

Myoepithelial cells are normal constituent of the salivary acini and smaller ducts, and are found between the epithelial cells and the basement membrane. Microscopic examination shows that myoepithelial cells are thin and spindle-shaped and situated between the basement membrane and epithelial cells. Ultrastructurally they possess a number of cytoplasmic processes that extend between and over the acinar and ductal-lining cells. They display features of both smooth muscle and epithelium, such as numerous microfilaments with focal densities in the cytoplasmic processes, and desmosomes which attach the myoepithelial to the epithelial cells. Neoplastic myoepithelial cells in both benign and malignant tumors can take several forms, including epithelioid, spindle, plasmacytoid, and clear, and this variability largely accounts for difficulties in histopathological diagnosis. This review article highlights the role of myoepithelial cells in salivary gland tumors.