Diagnostic Utility of Immunohistochemical Markers Trop2 and CD56 in Differentiating Follicular Derived Thyroid Lesions

Abstract

Background: Thyroid cancer is the most common malignant endocrine neoplasm worldwide. Diagnostic conflicts may occur regarding follicular derived thyroid lesions; therefore there is an increasing demand for using markers that help in attaining correct diagnosis. Trop2 is a transmembrane glycoprotein present in various epithelial malignancies. CD56 is a neural cell adhesion molecule that is expressed in the normal follicular epithelium of the thyroid gland.
Aim: To evaluate the diagnostic utility of immunohistochemical markers (Trop2 and CD56) in differentiating follicular derived thyroid lesions in Egyptian patients.
Materials and Methods: Expression of Trop2 and CD56 was evaluated immunohistochemically in 71 cases of follicular derived thyroid lesions; 35 benign lesions (10 cases nodular goitre (NG), 5 cases Graves’ disease and 20 cases follicular adenoma (FA)), 36 malignant cases (23 classic papillary thyroid carcinoma (PTC), 9 follicular variant papillary carcinoma (FVPC) and 4 cases of follicular carcinoma (FC)).
Results: Expression of Trop2 and CD56 loss revealed 80.5% and 83.3% sensitivity and 97.1% and 91.4% specificity respectively for differentiating malignant from benign follicular derived thyroid lesions while these markers showed 90.6% and 84.4% sensitivity and 97.4% and 84.6% specificity respectively in PTC versus all other studied lesions.
Conclusion: Trop2 and CD56 are valuable in the differentiation between benign and malignant follicular derived thyroid lesions with good sensitivity and specificity, while Trop2 is better in the distinction of PTC from other lesions. All PTC cases revealed either Trop2 positivity or CD56 loss raising the sensitivity to 100%.