Reproducibility of 'The Bethesda System for reporting Thyroid Cytopathology': A MultiCenter Study with Review of the Literature.

Background: To achieve the standardization of the thyroid FNA reporting, the National Cancer Institute (NCI) hosted the "NCI Thyroid Fine Needle Aspiration State of the Science Conference", which led to the formation of 'The Bethesda System for Reporting Thyroid Cytopathology' (TBSRTC).

Material And Methods: The present study was undertaken by 2 experts in thyroid FNA, who in a double blinded fashion, examined and re-classified 80 random FNA cases according to the 6 levels of TBSRTC for an inter-observer review, to study and assess the new terminology for ease of reproducibility and to note the rate of disagreement overall or in any particular category. The FNAs were reclassified in a double blinded fashion according to the 6 levels of TBSRTC which are: non diagnostic (ND); benign; atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS); follicular neoplasm/suspicious for a follicular neoplasm (FN/SFN), Hurthle cell type/suspicious for a follicular neoplasm, Hurthle cell type (FNHCT/SFNHCT); suspicious (SUS), and malignant.

Results: In the present study, the maximum number of cases was reclassified under the benign category (61.25% cases), followed by the FN/ SFN category and the AUS/FLUS category (11.25% and 10.00% respectively). An agreement was reached in 66 cases (82.5%); the experts disagreed in 14 cases-17.5% (where 1 expert did not agree with the other). Individually; a 93.87% agreement was noted for the lesions in the benign category, for 50% lesions in the AUS/FLUS category, for 66.66% lesions in the FN/SFN and the SUS categories, for 71.42% lesions in the FNHCT/ SFNHCT categories and for 100% lesions in the ND and the malignant categories. Thus, the maximum disagreement was noted in the AUS/FLUS category.

Conclusion: The implementation of TBSTRC which stands for a unique, international and a universal terminology for reporting the thyroid cytology; should be encouraged in our country, because of its relative ease of reproducibility. Although there was a great deal of agreement in implementing TBSTRC in the present study; disagreements were seen in the categories of AUS/FLUS and FN/SFN in the study which was conducted at our centre. This corroborated with the findings of the studies which were done elsewhere.