Diagnostic accuracy of fine needle aspiration cytology of thyroid nodules.

Background Routine application of fine needle aspiration cytology (FNAC) has decreased unnecessary referral of thyroid nodules for surgical treatment and has also increased the cancer rates found in surgery materials. Success of thyroid FNAC depends on skilled aspiration, skilled cytological interpretation and rational analysis of cytological and clinical data. The aim of this study was to determine the diagnostic accuracy rates of thyroid FNAC results obtained in our institution. Methods The data from FNAC and thyroidectomy reports of patients presenting with goiter and who had been evaluated from 1st January 2014 to 1st March 2018 were used. There were 149 patients in total who had undergone thyroidectomy following FNAC. The Bethesda System for Reporting Thyroid Cytology was used in all cytological diagnoses. Results The sensitivity of thyroid FNAC for malignant cases was 57.89%, specificity was 88.10%, false-positive rate was 11.90%, false-negative rate was 42.11%, positive predictive value was 52.38%, negative predictive value was 90.24% and accuracy rate was 82.52%. "Focus number" variable was detected as the factor that affected the accurate prediction of FNAC and thyroidectomy results by the pathologist. Conclusions This study showed that there was a moderate conformity between thyroid FNAC and thyroidectomy cyto-histopathological diagnosis in malignant cases. As two or more nodules have a negative effect on the physician's diagnosis of malignant nodules, we think that a more sensitive approach is needed in the determination of these cases. Sampling defects may affect this non-matching.