Stromal and epithelial syndecan-1 expression in benign and malignant salivary gland tumors: which is more reflective of behavior?

Abstract

IntroductionSalivary gland tumors are a diverse group of lesions, with various origins and extremely different behaviors, leading to a variety of outcomes for patients. Therefore, the need to discover novel markers with the ability to predict the behavior of benign and malignant salivary gland neoplasms is crucial. Syndecan-1 is a cell-surface protein with significant roles in various aspects of tumor function. Its expression in salivary gland neoplasms, especially their stromal component, has not been investigated. ObjectivesWe aimed to assess the immunopositivity of syndecan-1 in epithelial and stromal components of salivary gland neoplasms and to compare it between benign and malignant subtypes in addition to evaluating its correlation with clinicopathologic parameters. Methods133 salivary gland tumors were immunohistochemically stained with syndecan-1 and the intensity and percentage of this protein was determined, compared between the tumors and correlated with clinicopathologic factors. ResultsStatistical analysis of lesions with a sufficient sample size showed significant differences in percentage and intensity between both epithelial and stromal components of all tumors (p<0.05). Pairwise-comparisons demonstrated significantly higher staining-percentage of epithelial cells (p=0.02) in Warthin’s tumor compared to pleomorphic adenoma and adenoid cystic carcinoma. Similarly, significantly higher staining intensities and/or percentages was observed in mucoepidermoid carcinoma and adenoid cystic carcinoma compared to pleomorphic adenoma and Warthin’s tumor (p<0.05). Of the clinicopathologic factors, there was only a significant negative correlation between stromal percentage of mucoepidermoid carcinoma and age and a significant difference between stromal intensity+percentage of adenoid cystic carcinoma and gender (p<0.05). ConclusionsAccording to our findings we postulate that stromal syndecan-1 correlates with the behavior of salivary gland tumors, with malignant neoplasms demonstrating a higher expression, indicating a role for syndecan-1 in invasion and metastasis.