Research ArticlesDiagnostic Value of TROP2 Expression in Papillary Thyroid CarcinomaSaffar, Hana MD*; Jahanbin, Behnaz MD*; Ameli, Fereshteh MD*; Farhang, Fatemeh MD*,†; Tavangar, Seyed M. MD†; Saffar, Hiva MD†Author Information *Department of Pathology, Imam Khomeini Hospital Complex †Department of Pathology Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran This research has received funding from Tehran University of Medical Sciences as residency thesis. The authors declare no conflict of interest. Reprints: Hiva Saffar, MD, Department of Pathology, Shariati Hospital, Tehran University of Medical Sciences, Tehran 1411713135, Iran (e-mail: [email protected]). Applied Immunohistochemistry & Molecular Morphology: March 2021 - Volume 29 - Issue 3 - p 218-222 doi: 10.1097/PAI.0000000000000886 Buy Metrics Abstract Papillary thyroid carcinoma (PTC) represents the most common primary malignant thyroid lesion in all age groups. As diagnosis of PTC could be challenging in some cases and borderline nuclear features could be seen in some benign mimickers, several immunohistochemical markers are proposed to be helpful for making the correct diagnosis. In this study the authors investigated the diagnostic value of transmembrane glycoprotein (TROP2) for differentiating PTC from other thyroid follicular lesions. A total of 155 total thyroidectomy specimens including 84 cases of PTC and 71 cases of non-PTC were investigated. Among non-PTC group, 45 cases were follicular neoplasms and 26 cases were Hashimoto thyroiditis. TROP2 expression was observed in 82 of 84 cases of PTC group. In contrast only 5 cases of non-PTC group, all from Hashimoto thyroiditis specimens, showed positive expression. The sensitivity, specificity, positive predictive value, and negative predictive value of TROP2 for diagnosis of PTC was 98%, 93%, 94%, and 97%, respectively. The authors concluded that high sensitivity and specificity of TROP2 as well as its uniform negative reaction in follicular adenoma and carcinoma makes it a valuable immunohistochemical marker for diagnosis of PTC. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.