Pathophysiology of myoepithelial cells in salivary glands.

Myoepithelial cells (MECs) are considered to be a key participant in most salivary gland diseases, particularly tumors. MECs structurally resemble both epithelial cells and smooth muscles. Diagnostic dilemmas caused are due to inadequacy of characterizing the wide spectrum of morphologic and immunologic features which are different for both normal and neoplastic MECs. This article discusses the development, functions and structure of both normal and neoplastic MECs, their staining properties and differences in the morphologic and immunophenotypic properties of the MEC in detail. It also describes the role of MEC in pathogenesis and morphogenesis of various nonneoplastic and neoplastic salivary gland lesions and thereby are responsible for the myriad histopathology of salivary gland tumors.