Primary epithelial tumors of salivary glands - Histomorphological and immunohistochemical implications

The predominant amount of research dealing with salivary gland tumors has been the histogenesis of different epithelial tumors and supplementally immunohistochemical and ultrastructural assessments. Salivary gland tumors, both benign and malignant, showed most heterogeneity of histopathology and histochemistry that considered biological roles of epithelial-mesenchymal interactions as biosynthesis of extracellular matrix proteins. Many primary salivary gland tumors histologically consist of most epithelial structures associated with modified or neoplastic myoepithelial cells which have been recognized to be complex properties of epithelial, mesenchymal and other structural components, although normal myoepithelial cells showed more simple properties. Recently, modified or neoplastic myoepithelial cells in salivary gland tumors were not shown to originate from myoepithelial cells and were possible ductal cells in origin. However those uncomprehensive or non-distinct properties of histogenetic concepts in human salivary gland tumors can not be instead of animal studies. Moreover rodent submandibular glands have shown specific structures as granular convoluted tubules which are the source of growth factors or biologically active peptides, and human specimens may have a possibility to synthesize or produce growth factors. Thus the present review deals with critical evidence or possible identification of specific target subjects during histogenesis of salivary gland tumors, as well as different histologic types of tumor lesions without common classification. With the continued interest of salivary gland research under pathologic implication, unique systems for identification or molecular manipulations of salivary gland tumors may provide new opportunities in the health sciences.