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].
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“…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].…”
Section: Discussionmentioning
confidence: 99%
“…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.…”
Salivary gland tumors, the second most common neoplasm of the mouth after squamous cell carcinoma, account for a significant proportion of tumors of the oral and perioral regions. An unusual case of adenoma presented as a solitary intraoral palatine mass in a 32-year-old woman is reported here. The tumor was interpreted as an unusual pleomorphic adenoma because of the presence of exuberant squamous metaplasia, clinically mimicking squamous cell carcinoma. Moreover, the presence of cystic structures filled with keratinized material was also salient feature. Pleomorphic adenomas may occasionally display focal squamous metaplastic changes; when extensive, it presents the potential for misinterpretation of the histology as indicative of well-differentiated squamous cell carcinoma.
“…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].…”
Section: Discussionmentioning
confidence: 99%
“…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.…”
Salivary gland tumors, the second most common neoplasm of the mouth after squamous cell carcinoma, account for a significant proportion of tumors of the oral and perioral regions. An unusual case of adenoma presented as a solitary intraoral palatine mass in a 32-year-old woman is reported here. The tumor was interpreted as an unusual pleomorphic adenoma because of the presence of exuberant squamous metaplasia, clinically mimicking squamous cell carcinoma. Moreover, the presence of cystic structures filled with keratinized material was also salient feature. Pleomorphic adenomas may occasionally display focal squamous metaplastic changes; when extensive, it presents the potential for misinterpretation of the histology as indicative of well-differentiated squamous cell carcinoma.
“…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).…”
Section: Discussionmentioning
confidence: 99%
“…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).…”
TGF-ß-stimulated clone-22 (TSC-22) was reported to be a differentiation-inducing factor which negatively regulates the growth of salivary gland cancer cells. In the present study, we examined the expression of TSC-22 in salivary gland tumors by immunohistochemistry. In pleomorphic adenoma (PA), most of the sparse myoepitheliallike tumor cells, which are considered as the differentiated cells because they produce extracellular matrix, expressed TSC-22. However, only a limited number of cases of the solid myoepithelial-like tumor cells in PA, which are considered as the growing cells, expressed TSC-22. In adenoid cystic carcinoma (ACC), inner ductal cells in the tubular structure, strongly expressed TSC-22, though the outer myoepithelial-like tumor cells did not express TSC-22. In the cribriform structure, myoepithelial-like tumor cells did not express TSC-22. However, a small ductal structure in the micro-cyst wall strongly expressed TSC-22. Sparse type myoepithelial-like tumor cells in ACC also expressed TSC-22. In mucoepidermoid carcinoma, epidermoid tumor cells and mucous-producing tumor cells in mucoepidermoid carcinoma frequently expressed TSC-22. Thus, the expression of TSC-22 was frequently observed in the cells with differentiatedphenotypes, although rarely in the cells with growing potentials. These results suggest that TSC-22 may play an important role in maintaining the differentiated phenotype in salivary gland tumors.
“…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.…”
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