Emerin expression in well differentiated epithelial lesions of thyroid: Implications in papillary thyroid carcinoma diagnosis and predicting malignant behavior

Recently, it has been reported that identifying nuclear membrane irregularities with anti-emerin antibody is useful for papillary thyroid carcinoma diagnosis. However, literature regarding the significance of emerin immunohistochemistry in thyroid is limited. We evaluated the diagnostic accuracy of the well-established nuclear alterations, nuclear protrusions and recently described nuclear shapes (garlands and star-like shapes) with emerin immunohistochemistry and hematoxylin- eosin stain in thyroid lesions. We further evaluated the diagnostic accuracy measures of tissue microarrays evaluated with both stains, to detect whether emerin immunohistochemistry improves the diagnostic accuracy for papillary thyroid carcinoma. For papillary thyroid carcinoma, pseudo- inclusions were best performers with emerin (diagnostic accuracy: 0.91), whereas with hematoxylin- eosin diagnostic accuracy of grooves was the highest (0.92). For follicular variant of papillary thyroid carcinoma, with both stains, predominately oval nuclear shape had the best diagnostic performance (diagnostic accuracy: 0.95). Nuclear protrusions were poor identifiers for papillary thyroid carcinoma. However, with emerin immunohistochemistry, they could successfully identify malignancy in 83 % of the cases. Using emerin immunohistochemistry, in addition to hematoxylin- eosin improved the diagnostic accuracy for papillary thyroid carcinoma when compared to hematoxylin- eosin evaluation only (sensitivity: 0.70 vs 0.86, negative predictive value: 0.81 vs. 0.94, diagnostic accuracy: 0.87 vs. 0.94). Consistent with the previous literature, our findings indicate that emerin immunohistochemistry may be used as an adjunct diagnostic method to identify papillary thyroid carcinoma. Additionally, we suggest that nuclear protrusions detected with emerin imunohistochemistry may be used as indicators of malignant behavior in small tissue samples of thyroid.