The ultrastructural aspects of neoplastic myoepithelial cell in pleomorphic adenomas of salivary glands

Abstract

The salivary gland pleomorphic adenoma is a benign epithelial neoplasm, histologically characterized by a great diversity of morphological aspects. According to literature data, the pleomorphic adenoma represents 45-74 % of all the salivary gland tumors [1][2][3][4]. At the Armed Forces Institute of Pathology (AFIP) the pleomorphic adenomas represent 60 % of the benign tumors from all the salivary gland sites: 61 % of the major gland tumors and 54 % of the minor gland tumors [5]. AbstractThe purpose of this study has been to establish the major ultrastructural aspects of the myoepithelial cell and the myoepithelial-like cells proliferated in the pleomorphic adenomas of salivary glands. Thus, twelve benign pleomorphic adenomas of salivary glands have been studied by electron-microscopy transmission techniques. Our analysis has proved the proliferation of two major cellular populations, one of ductal type and one of myoepithelial type, which tried to reproduce the tubulo-acinar cytoarchitecture from the normal salivary glands. We have also noticed the key role of the so-called 'modified' myoepithelial cells from the periphery of the proliferating epithelial units in the genesis of the myxoid and chondromyxoid tumoral stromal areas. All these ultrastructural aspects have explained the great histological diversity of these salivary gland neoplasms as well as the key role of the myoepithelial cell in its histogenesis.

Pleomorphic Adenoma with Exuberant Squamous Metaplasia and Keratin Cysts Mimicking Squamous Cell Carcinoma in Minor Salivary Gland

“…PA is characterized by great histologic diversity; however, PA with exuberant squamous metaplasia is uncommon and can be diagnostically challenging [1][2][3]9]. Focal squamous metaplasia in PA can be related to ischemia [16], and may be found in about 25% of the PA [8].…”

“…Histological diversity is the hallmark of pleomorphic adenoma (PA). Its histological patterns may vary considerably among different parts of the same tumor [1]. Not only does the proportion between epithelial and chondromyxoid stroma vary, but some metaplastic variations also occur in the epithelial and stromal components.…”

Expression and cellular localization of TSC-22 in normal salivary glands and salivary gland tumors: Implications for tumor cell differentiation

“…It is well known that salivary gland tumors consist of several tumor cell components, such as myoepithelial-like tumor cells, duct-like tumor cells, acinus-like tumor cells, epidermoid-like tumor cells, mucin-producing tumor cells and tumor cells with mesenchymal differentiation (17). There are several reports concerning the direction of differentiation in salivary gland tumors or the tumor stem cells of salivary gland tumors (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33). Sato et al established a cultured salivary gland tumor cell line, HSG (21) and investigated the differentiation potentials of HSG cells (22)(23)(24)(25)(26).…”

“…It was concluded that the HSG cells or transformed intercalated duct cells might be the tumor stem cells for several components of the salivary gland tumors. On the other hand, under the basis of the observation of histopathology of salivary gland tumors, Aigner et al (27) and several other pathologists (28)(29)(30)(31)(32)(33) reported that myoepithelial-like tumor cells might be the tumor stem cells or procurer cells for several components in salivary gland tumors (22)(23)(24)(25)(26)(27)(28).…”

DNA methylation polymerase chain reaction (PCR) array of apoptosis-related genes in pleomorphic adenomas of the salivary glands

“…1 Salivary gland PAs show great histologic variation and present 2 major proliferating cellular types: luminal and abluminal cells (with myoepithelial cell morphology). 2 Molecular heterogeneity in these tumors has also been proved. 3 PAs can recur or undergo malignant transformation, 4,5 and the clarification of their molecular pathogenesis may help improve the understanding of such phenomena.…”