BACKGROUND: The recently introduced monoclonal V600E antibody (clone VE1) is likely to be an alternative strategy for detecting this mutation in thyroid lesions. Although VE1 immunostaining and molecular methods used to assess papillary thyroid carcinoma in surgical specimens are in good agreement, evaluation of VE1 in cytology and cell block samples is rarely performed, and its diagnostic value in cytology has not been well established. In this study, we sought to determine if VE1 is suitable for fine needle aspiration (FNA) and cell block methods.
METHODS: A total of 86 patients who had BRAF V600E mutations were investigated with molecular and immunocytochemical (ICC) analysis in 45 FNA and 41 cell blocks. In total, 83 (96.5%) patients underwent surgical treatment. Assessment of BRAF V600E mutation status was performed in 72 (83.7%) cases.
RESULTS: Among the 72 cases analysed, 54 cases agreed (ICC+/BRAF+ or ICC-/BRAF-), seven cases were false positive (ICC+/BRAF-) and 11 cases were false negative (ICC-/BRAF+). False negative cases were not detected in the cell block method. The statistical analysis showed that sensitivity and specificity of ICC for detecting the BRAF V600E mutation were 61% and 77% in FNA samples and 100% and 73% in cell block.
CONCLUSION: The use of antibody VE-1 is a reliable method and a negative result of VE1 immunostaining might help to save time and money, restricting the molecular test to antibody-positive cases only. The identification of the aggressive variants of papillary carcinoma might be enabled by the expression of the antibody in neoplastic cells with tall cell features.