Epithelial Membrane Antigen in Papillary Thyroid Carcinoma and Multinodular Goiter; a Marker of Discrimination

Papillary thyroid cancer is the most common type of thyroid malignancies. For a more accurate diagnosis, immunohistochemistry has been used widely in recent years. Epithelial membrane antigen has been detected in several benign and malignant lesions, and its use as a marker of malignancy has been sought in some studies.

The current study aimed to determine the presence and level of expression of epithelial membrane antigen in papillary thyroid carcinoma and multinodular goiter.

Eighty-five samples of papillary thyroid carcinoma and 40 cases of multinodular goiter were stained histochemically for epithelial membrane antigen. The intensity of staining was classified in a semi-quantitative manner (1+ to 4+). Demographic data of the index cases, history of metastasis, and lymph node involvement, if any, were collected as well.

All PTCs and 87.5% of MNGs were positive for EMA. EMA was expressed more strongly in PTCs than in MNGs (P < 0.00). EMA reactivity was directly associated with lymph node involvement, capsular invasion, and size of the tumor (P = 0.008, P < 0.001, and P < 0.001, respectively). The intensity level of 2 or higher had high specificity for differentiating PTC from MNG.

Strong expression of EMA may be a good marker of malignancy in differentiating PTC from MNG. This marker may also be regarded as an index of invasive behavior of PTC.