The Bethesda terminology for reporting thyroid cytopathology: from theory to practice in Europe

A 2007 conference held at the National Cancer Institute, Bethesda, Md., USA, proposed a new terminology for classifying the results of thyroid fine-needle aspiration (FNA) - The Bethesda System for Reporting Thyroid Cytology (TBSRTC). The need to standardize thyroid FNA terminology was emphasized during the 35th European Congress of Cytology in 2009. An interobserver review study to assess the new terminology for analyzing the results of thyroid FNA was organized by the scientific committee of the European Federation of Cytology Societies.

Four experts in thyroid FNA examined and classified 116 FNAs according to the 6 levels of TBSRTC which are: nondiagnostic (ND); benign; atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS); follicular neoplasm/suspicious for a follicular neoplasm (FN/SFN), with those of Hürthle cell type reported as follicular neoplasm, Hürthle cell type/suspicious for a follicular neoplasm, Hürthle cell type (FNHCT/SFNHCT); suspicious (SUS), and malignant.

The total consensus was 62.1%; the cytopathologists disagreed on 44 cases, including 8 cases of AUS/FLUS and 18 of FN/SFN; 59% of the cases had no consensus. They agreed on 73 and 80% of the cases classified as benign and malignant, respectively, and on 58.3% of the SUS cases. The percentage of no consensus for each expert was between 32 and 39%.

Disagreement regarding the use of TBSRTC terminology for classifying the results of thyroid FNA mainly occurred in the most-often criticized categories of AUS/FLUS and FN/SFN.