Diagnostic and prognostic value of immunocytochemistry and BRAF mutation analysis on liquid-based biopsies of thyroid neoplasms suspicious for carcinoma

Abstract

Objective: In the field of fine-needle aspiration cytology, the category of suspicious for malignancy (SM) thyroid lesions, that bears 55-85% risk of malignant histology, is a challenging topic in which morphology alone is not always able to make a correct diagnosis. Recently, immunocytochemistry (ICC) has been referred to as helpful in differentiating low- and high-malignant risk lesions and BRAF activating mutations have been identified in a significant amount of papillary thyroid carcinomas (PTC). The introduction of the liquid-based cytology (LBC) may simplify the application of these techniques to thyroid cytology. Design: Our aim is to evaluate the diagnostic and prognostic role of both ICC and BRAF mutation for the SM category on LBC. Methods: From October 2010 through June 2011, 113 LBC cytological cases (including 37 SM and 76 PTC) underwent surgery. All cases were studied for BRAF mutation and ICC. Results: ICC resulted positive in 26 (86.6%) histologically malignant SM with 15 of which (40.5%) expressing a BRAF mutation. Overall, 63 cases showed a BRAF mutation resulting in PTC. Concerning the prognostic role of BRAF mutation for the two categories, we reported a significant correlation with multifocality, nodal involvement and extra-capsular invasion (P<0.0001). Conclusions: Special techniques such as ICC and molecular markers might be successfully carried out on LBC-processed material. For both categories, ICC is more sensitive whereas BRAF analysis is an interesting support due to its high specificity adding a prognostic value in both SM and PTCs. © 2013 European Society of Endocrinology.