Diagnostic value of differential expression of CK19, Galectin-3, HBME-1, ERK, RET, and p16 in benign and malignant follicular-derived lesions of the thyroid: an immunohistochemical tissue microarray analysis.

Several immunohistochemical markers have been used to aid in the diagnosis of follicular-derived lesions of the thyroid (FDLT). In this study we analyze the diagnostic efficacy of an immunopanel of antibodies to cytokeratin-19 (CK19), galectin-3 (GAL-3), HBME-1, anti-MAP kinase (ERK), ret-oncoprotein (RET), and p16 using a tissue microarray consisting of both benign and malignant FDLT. The study cohort consisted of 90 cases of FDLT (53 benign, 37 malignant) embedded in a microarray and immunostained with antibodies to CK19, Gal-3, HMBE-1, ERK, RET, and p16. Staining was scored as positive when >25% of the lesional cells showed positive immunostaining. HMBE-1 was expressed in 70% of malignant and 10% of benign FDLT (p value: <0.0001). CK19 and GAL-3 were positive in 70% and 73% of malignant lesions, respectively, and 34% of benign FDLT (p value 0.0005 and 0.0015, respectively). ERK was positive in 4% of the benign and 32% of the malignant cases (p value 0.0002). p16 was expressed in 2% and 46% of the benign and malignant lesions, respectively (p value 0.0001). RET positivity was identified in 15% of the benign lesions and 27% of the malignant cases (p value 0.0016). HBME-1, ERK, and p16 were more specific for malignancy, whereas CK19 and GAL-3 stained benign lesions with a higher frequency and were not specific for malignant FDLT. RET-oncoprotein showed poor sensitivity and specificity.