Monoclonal antibody‐detected vimentin distribution in pleomorphic adenomas of salivary glands

Abstract

To evaluate the participation of myoepithelial components in pleomorphic adenomas, an immunohistochemical study was carried out using monoclonal antibodies to vimentin. Of a total of 80 cases, 50 tumors gave positive staining, 5 tumors very slight, and 25 tumors negative staining for vimentin. Localization patterns for vimentin were divided into 3 classes: 1) vimentin staining in fibrous stromal tissue; 2) variable intensities of vimentin staining were found in the outer layers of tumor cells in tubuloductal structures (some of which were spindle cells connected to modified myoepithelial cells which also gave variable vimentin staining); and 3) modified myoepithelial cells and chondroidlike cells displayed strongly positive staining for vimentin. Typical histologic features of pleomorphic ademomas, i.e., tubulo‐ductal or duct‐like structures were characterized by positive vimentin staining in outer tumor cells and by a positive keratin reaction in the luminal tumor cells. In tumors devoid of stromal connective tissues and the near absence of well‐developed, or modified myoepithelial cells, vimentin staining was absent.

Heterogeneity of keratin distribution as revealed by monoclonal antibodies in salivary pleomorphic adenomas.

“…that the outer tumor cells of duct-like structures in pleomorphic adenomas, irrespective of their cell shape, originate from myoepithelial cells; however, direct evidence has not been provided. Immunohistochemical studies have noted that the outer tumor cells are positive for vimentin (29), and showed co-expression with keratin and vimentin (4,24). These immunohistochemical characteristics of outer tumor cells rather resemble those of modified myoepithelial cells.…”

Myoepithelium of salivary glands

“…The solution to the problem seemed at hand when it was discovered that myoepithelial, mesenchymal, and muscle cells could be distinguished immunohistochemically in normal glands and tissues by their intermediate filaments, namely, keratins, vimentin, and desmin, respectively (Franke et al, 1978(Franke et al, , 1980. This hope was dashed when it was found that, very frequently, MEC-like cells in salivary gland neoplasms contain both keratin and vimentin (Burns et al, 1988;Caselitz et al, 1984;Dardick et al, 1985Dardick et al, , 1989Geiger et al, 1987;Mori, 1991;Morinaga et al, 1987;Ogawa et al, 1990;Warner et al, 1985;Yamada et al, 1988). Desmin has not been localized to MEC (Franke et al, 1980;Mori, 1991).…”

Myoepithelial Cell Markers in Salivary Gland Neoplasms

“…Nevertheless, later studies showed that neoplastic MEC may not express oc-SMA [4][5][6][7][8][9]. Vimentin has also been used as a neoplastic MEC marker [10][11][12][13][14][15], and was indicated as an early marker of myoepithelial differentiation, being present in all morphologic types that the MEC may assume [9,16,17]. Later, it was shown that other neoplastic salivary gland cells may also express vimentin, as demonstrated in cells of ductacinar segment present in polymorphous low-grade adenocarcinoma [ 1 8].…”