TROP2: a potential marker in diagnosis of thyroid neoplasms

Background and objectives: The human trophoblast cell surface antigen (TROP-2), a transmembrane glycoprotein, has recently been investigated as a valuable marker of thyroid epithelial neoplasms. In this study, we aimed to demonstrate the diagnostic utility of TROP2 in thyroid neoplasms.

Methods: A total of 308 cases, including 170 cases of different PTC variants, 50 cases of benign and non-neoplastic lesions, and 86 cases of other neoplasms (NIFT-P, poorly differentiated thyroid carcinoma, anaplastic thyroid carcinoma, follicular thyroid carcinoma, Hürthle cell carcinoma, and medullary thyroid carcinoma), were included in this study. Only membranous staining with TROP2 was considered positive.

Results: In PTC, classical (n = 35), tall cell (n = 41), follicular (n = 39), solid (n = 19), hobnail (n = 10), Warthin-like (n = l0), columnar (n = 7), and oncocytic variant (n = 9) were 100%, 97.6%, 5.1%, 42.1%, 90%, 90%, 28.6%, and 33.3% positive, respectively. A negative reaction was observed in all 50 cases of benign and non-neoplastic lesions and also in surrounding normal thyroid tissue in all cases. Negative reactions were observed in 83 (n = 86) of other thyroid neoplasms including NIFT-P (n = 20), poorly differentiated thyroid carcinoma (n = 10), anaplastic thyroid carcinoma (n = 10), follicular thyroid carcinoma (n = 18), Hürthle cell carcinoma (n = 18), and medullary thyroid carcinoma (n = 10). Only focal positivity was observed in three Hürthle cell carcinoma cases.

Conclusion: TROP2 was a helpful marker for differentiating PTC, especially in the classic, tall cell, hobnail, and Warthin-like variants, benign and non-neoplastic lesions, and other neoplasms of the thyroid.