• thyroid;
  • fine needle aspiration;
  • Bethesda

Recently, a six-tiered diagnostic risk classification system was created based on the recommendations of the National Cancer Institute (NCI) sponsored NCI Thyroid Needle Aspiration State of the Science Conference at Bethesda, MD in October 2007. The objective of the current study was to compare the frequency distribution of the various diagnostic categories to evaluate its diagnostic performance before and after implementation of The Bethesda System (TBS). A total of 5,897 thyroid Fine needle aspirations (FNAs) were reviewed; 3,207 were from 2008 after TBS implementation, and 2,690 were from 2007 immediately before TBS implementation. Follow-up consisted of reviewing corresponding histologic results. The rates of “Nondiagnostic” specimens and cases with a diagnosis of “Follicular Neoplasm” decreased from 13.1 to 11.1% and 8.6 to 5.5%, respectively, after implementation of TBS, while the rate of negative specimens increased from 68.2 to 73.8%. The other categories remained relatively stable. In addition, there also was a significant decrease in the use of noncommittal descriptive diagnoses. The diagnostic performance of thyroid FNA in identifying a neoplastic process as measured by area under the receiver operating characteristic curve increased from 0.88 to 0.89; the difference was statistically significant (P=0.03). Implementation of TBS showed a significant reduction of: nondiagnostic thyroid FNAs, of FNAs with a diagnosis of “Follicular Neoplasm,” as well as cases with descriptive noncommittal diagnoses. TBS results in improved diagnostic performance and therefore more consistent and uniform reporting of thyroid FNA. Diagn. Cytopathol. 2013;41:858–863. © 2013 Wiley Periodicals, Inc.