Evaluation of Thyroid Fine-Needle Aspiration Biopsies according to Cytological Methods and Comparison with Histopathological Diagnosis

OBJECTIVES: In this study, we aim to compare the results of aspiration of thyroid nodules evaluated according to the Bethesda category (BC) with tissue diagnoses in the operation materials and to compare the sensitivity, specificity and accuracy rates according to cytology methods. METHODS: The previous fine-needle aspiration biopsy (FNAB) of thyroid nodules of 879 cases diagnosed histopathologically between 2010 and 2017 was examined. The FNAB results determined according to the Bethesda system were matched with tissue diagnoses, sensitivity, specificity, and accuracy rates were investigated according to cytology methods. RESULTS: Sensitivity, specificity, Positive predictive value (PPV), Negative predictive value (NPV) and accuracy rates were found in all FNAB results (in units of %; Sensitivity; 84.7, Specificity; 81.1, PPV; 74.1, NPV; 89.2, Accuracy; 82.5). All of the cytological evaluation methods of thyroid FNABs were found to be reliable and effective (Generally, the results are 80% and above). Specificity and accuracy rates were close to the general average (82.5%) in all methods. However, in cases evaluated with liquid base cytology (LBC) method and in addition to LBC or conventional smear (CS), the sensitivity rates in cases where cell block (CB) were evaluated together were higher than cases in which LBC and CS were used alone (92.6% and 91.0%). When examined statistically, there was no significant difference concerning sensitivity, specificity and accuracy rates of cytological methods (p>0.05, respectively, p=0.576, 0.065, 0.643). CONCLUSION: In cytopathology, when evaluating thyroid aspirations, it is seen that the LBC method is used instead of CS. In our study, we recommend the use of the LBC method, which seems to have the highest sensitivity (taking into account its technical advantages), instead of CS. However, we think that both CS and LBC methods should be evaluated by supporting them with cell block sections.