A histopathological and immunohistochemical study of cell adhesion factors in pleomorphic adenoma: mesenchyma-like changes of epithelial tumor cells

Abstract

The purposes of this study were to clarify morphological characteristics of tissue diversity of salivary pleomorphic adenomas (PA), and to examined cell adhesion and formation of mesenchyma-like tissue using histopathological and immunohistochemical methods. Histopathologically, tumor parenchyma showed ductal epithelium-like cells on the inner side which enclosed the lumen (first layer), surrounded by stratified myoepithelium-like cells (second layer). In the outer part of the second layer, myoepithelium-like cells were dispersed (third layer) toward the mesencyma-like tissue. Immunohistochemically, E-, N-cadherins and β-catenin positive tumor cell rates decreased as they transitioned from the first to third layers, and the ratio of N-cadherin positive cells remained higher than that of E-cadherin in the third layer. Further, vimentin, actin, and p63 positive cell rates increased and collagen type IV positive basement membrane tended to disappear as they transitioned from the first to third layers. These findings suggested that the epithelial tumor cells changed their characteristics to mesenchymal cells.