Clinical Usefulness of SurePath(TM) Liquid-based Cytology in Thyroid Fine Needle Aspiration: Comparison with the Conventional Smear in Diagnostic Efficacy and Applicability of BRAF Mutation Test

ABSTRACT

BACKGROUND: Recently, liquid-based cytology (LBC) has been introduced as an alternative to the conventional smear (CS) technique in thyroid fine needle aspiration, due to its diagnostic convenience. METHODS: We assessed 77 cases of thyroid fine needle aspiration using the SurePath(TM) method (SP) as LBC and CS via split-sample techniques. BRAF mutation tests were carried out via polymerase chain reaction and pyrosequencing immediately after diagnosis or a delay of more than one year. RESULTS: In a comparison between SP and CS, the rate of concordance between SP and CS was as high as 84.4% (kappa value, 0.754). In comparison with histologic diagnosis, the overall sensitivity was 100% for both. The specificity was 62.5% for SP and 56.3% for CS. Relative to CS, papillary carcinomas on SP slides revealed more accentuated nuclear irregularities, nucleoli, and reduced nuclear size. In contrast to CS, the delayed BRAFV600E mutation test using SP slides after 1-2 years failed. The use of new primers amplifying shorter product size could help the delayed test achieve success. CONCLUSIONS: Differences in the diagnostic efficacy of SP and CS were negligible. The failure of the delayed BRAF mutation test on the SP slides might be associated with DNA degradation.