Evaluation of GARP Immunohistochemical Expression in Papillary Thyroid Carcinoma

Abstract Background Glycoprotein A repetitions predominant (GARP) is a novel trans-membrane protein, highly expressed on the surface of regulatory T cells (Tregs). Tregs are a subset of immunosuppressive T-lymphocytes that play a major role in inhibiting antitumor immune response. Many studies documented increased GARP expression in various tumors. Our study was designated to evaluate the immunohistochemical (IHC) expression of GARP in differentiated thyroid carcinomas and their tumor infiltrating lymphocytes (TILs) in comparison to its expression in other benign and low-risk lesions and to assess the potential diagnostic role of GARP IHC expression in different thyroid lesions. Material and Methods Sixty-nine cases of different thyroid lesions subgrouped into: 37 cases of malignant thyroid neoplasms, 25 cases of benign thyroid lesions and 7 cases of low-risk neoplasms collected from pathology department laboratories of Ain Shams university hospitals during the period from January 2017 to December 2021 and stained immunohistochemically for GARP. IHC expression of GARP was evaluated in thyroid epithelial cells and TILs. The expression of GARP was correlated with the different clinicopathological parameters. Results GARP expression discloses significant statistical difference between the three studied groups (p