Immunohistochemical expression of CD44v6 in differentiated thyroid carcinomas

Background: CD44 is a polymorphic family of cell surface proteoglycans and glycoproteins implicated in cell-to-cell and cell-to-matrix adhesion interactions and tumor metastasis. Aim: This study was designed to histopathologically examine and immunohistochemically detect the expression of CD44v6 in differentiated thyroid carcinomas, and its association with clinicopathologic parameters. Methods: Forty different thyroid lesions constituted the material of this study. Cases were divided into a malignant (n=30) and a non-malignant group (n= 10). Immunostaining was manually performed using CD44v6 mouse monoclonal antibody. Results: CD44v6 expression was significantly higher in malignant compared to non-malignant lesions. This significance was not maintained when cases were categorized as neoplastic and nonneoplastic. Female sex and patients age 45 years were significantly associated with higher CD44v6 expression in the malignant group. Papillary thyroid carcinoma (PTC) showed higher CD44v6 expression than follicular thyroid carcinoma (FTC). CD44v6 immunopositivity did not significantly associate with the microscopic variant of PTC and FTC. Also, tumor size failed to relate significantly with CD44v6 expression within the subtypes of PTC and FTC. However, female sex, patient age 45 years, and tumor size between 1-4cms associated with significantly higher CD44v6 expression in the PTCs when compared to non-malignant lesions. In FTCs no significant relationship was observed between CD44v6 immunopositivity and patients’ age, sex, or tumor size. In the non-malignant group no significant relationship was found between CD44v6 immunopositivity and patients’ sex, or age. The background non-neoplastic thyroid tissue was CD44v6 negative in all cases of both groups except for 4 cases of PTCs.Conclusion: Deregulated expression of CD44v6 occurs in differentiated thyroid carcinomas and in benign thyroid nodules. Thus, further studies are warranted to investigate the diagnostic utility of CD44v6 expression in the differentiation of benign from malignant thyroid lesions. Also, the predictive value of CD44v6 deregulated expression in PTC and the occurrence of nodal metastasis needs further verification.