A Systemic Review on Similarities between Salivary and Mammary Gland Neoplasms and the Role of Antihormonal Therapy in Salivary Gland Tumors

Abstract

The matured salivary gland contains two types of cells, both luminal and abluminal cells. The luminal cells include acinar and ductal cells. The abluminal cells are myoepithelial and basal cells. 4 Unlike salivary glands, mammary glands undergo complex epithelial remodeling throughout puberty, pregnancy, lactation, and weaning. The mammary gland is a highly branched ductal structure having luminal cells and myoepithelial cells. 5 Each cell type in both mammary and salivary glands express a variety of markers that helps in the identification and characterization (Table 1) and (Table 2). [6][7][8] Salivary gland tumors are distinct in their wide variety of subcategorization and rarity in occurrence. The two most widely IntroductIonSalivary glands are complex tubuloacinar exocrine or merocrine glands mainly secrete saliva. The parotid gland is ectodermal, while submandibular and sublingual glands are endodermal in origin. All the minor salivary glands have mixed origins with both ectodermal and endodermal components. The epithelial cells determine the type of secretion produced by the gland and the mesenchymal cells contribute to the morphology of the gland. 1 Each developed gland consists of parenchyma, glandular secretory tissue, and stroma. The secretory units contain secretory cells which organize to form clusters called acini. These units can be either of the three types-mucinous, serous, and seromucinous. The secretions pass through the intercalated ducts, striated, excretory duct, and finally main excretory duct opening into the oral cavity. 2 The mammary gland contains both ectodermal and mesodermal components. The ectoderm forms a mammary line which resolves into placodes. These placodes invaginate into the mesenchyme and form the rudimentary ductal structure. The embryonic mammary mesenchyme provides the key signals for epithelial cell differentiation. This epithelial differentiation was demonstrated in reciprocal tissue recombination experiments in which 12 and 16th-day-old embryonic mammary epithelium was combined with salivary mesenchyme and grown in culture. These tissue recombinants produced epithelium that was morphologically resembling salivary glands. The rudimentary ductal system forms the terminal end buds which later differentiate to form myoepithelial cells. This system will develop into terminal ductolobular units with acini which are mainly mediated by hormones. 3