Abstract

BACKGROUND: Fine needle aspiration biopsy (FNAB) is a common and excellent procedure for the evaluation of thyroid lesions that require surgical resection. At times, the FNAB diagnosis can be difficult, particularly of follicular-patterned lesions. Previous studies have shown that some immunohistochemical (IHC) markers may be helpful in establishing more accurate diagnosis. In this study, our goal was to evaluate four of the recently investigated markers in differentiating benign from malignant thyroid nodules on FNABs. MATERIALS AND METHODS: We performed IHC staining of galectin-3, Ret oncoprotein (Ret), HBME-1, and cytokeratin 19 (CK19), on cell block sections of thyroid FNAB cases that had corresponding surgical resections. They included 44 benign lesions (37 hyperplastic or cellular nodules, HN; and 7 follicular adenomas, FA) and 27 malignant tumors (6 follicular carcinoma, FC; 19 classic papillary carcinoma, PTC; and 2 follicular variant of papillary carcinoma, FVPC). The stains were done according to the standard avidin-biotin-peroxidase method. RESULTS: Statistical analysis showed that immunoexpression was significantly higher in the malignant group for all four markers. The sensitivity for positive expression for all benign lesions versus malignant tumors was as follows: 10/44 (22.7%) versus 25/27 (92.6%) for galectin-3; 14/44 (31.8%) versus 23/27 (85%) for Ret; 12/44 (27.3%) versus 24/27 (88.8%) for HBME-1; and 13/44 (29.5%) versus 23/27 (85%) for CK19. The sensitivity and specificity was highest for galectin-3 (92.6% and 77.3%, respectively) followed by HMBE-1 (88.9% and 72.7%, respectively). When combining the markers' expressions, the panel of galectin-3 + HBME-1 showed the highest sensitivity and specificity (90.7% and 75%, respectively), but this was, however, lower than galectin-3 alone (92.3% and 77.3%, respectively). CONCLUSION: We conclude that galectin-3 is the best single marker in differentiating benign from malignant thyroid lesions with the highest sensitivity and specificity. The galectin-3 + HBME-1 was the best combination for distinguishing benign from malignant lesions. Because they were the best two independent and combined markers, we recommend the use of the galectin-3 + HBME-1 panel to enhance the diagnostic accuracy of follicular-patterned thyroid lesions on FNABs.