The histopathological features of salivary gland tumors on routine H&E are the gold standard for diagnosis.Tumors with somewhat equivocal histological features may need additional immunohistochemical markers for establishing final diagnosis.
Objective: To study the immunohistochemical pattern of SOX10 and CD 117 (c-KIT) in human samples of normal and neoplastic salivary gland tissues, trying to characterize and distinguish the various types of salivary gland tumors and to determine their origin from epithelial (luminal) and myoepithelial/basal (abluminal) cells of salivary glands.
Materials and Methods: Forty malignant salivary gland tumors [ten cases of mucoepidermoid carcinoma (MEC), 10 cases of adenoid cystic carcinoma (AdCC) , 8 cases of acinic carcinoma (AcC), 6 cases of polymorphous low grade adenocarcinoma (PLGA), 3 cases of carcinoma ex-pleomorphic adenoma (CXPA) and 3 cases of epithelial myoepithelial carcinoma (EMC)] and 22 benign tumors [12 cases of pleomorphic adenoma (PA) and 10 cases of Warthin tumor (WT)], in addition to 10 control cases of chronic sialadenitis were included in this study. Histopathological diagnosis was made on freshly prepared H&E sections followed by immunohistochemical application and analysis of c-KIT (CD117) and SOX10 markers.
Results: The mean age of the patients with salivary gland tumors was 48 ± 12 (mean SD) (range, 18-84) years. There were 33 male and 29 female patients. Eight cases of PA, 9 cases of AdCC, 6 cases of AcC and 4 cases of PLGA were positive for c-KIT. No significant difference between the positivity of c-kit expression between these four types of salivary gland tumors. Although the percent of positive tumor cells was different between them, however this difference was still insignificant. Other salivary gland tumors examined showed weak and focal c-KIT expression.
In normal human salivary gland tissue, SOX10 expression was specific to the nuclei of acini and both luminal and abluminal cells of intercalated ducts but not in other sites.SOX10 expression can differentiate salivary tumors into two subgroups in which acinic cell carcinomas, adenoid cystic carcinomas, epithelial-myoepithelial carcinomas, and pleomorphic adenomas, including the pleomorphic adenoma component of carcinoma (CXPA), were strong SOX10 positive, while mucoepidermoid carcinomas, PLGA and Warthin tumors were weak or negative for SOX10.
Conclusion: These results suggested that c-kit of no use in differential diagnosis between AdCC, AcC, PLGA and PA. Using of SOX10 may be helpful in diagnosis of some neoplastic lesions of salivary gland and may help in understanding the histogenesis of salivary gland tumors. SOX10 expression pattern of salivary gland tumors mirrors those of normal tissues, showing acinus and intercalated duct differentiation in a biphasic manner.
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