Evaluation of Bethesda System in Cytopathological Diagnosis of Thyroid Nodule and its Histopathological Correlation

Abstract

Introduction: Fine needle aspiration cytology (FNAC) is an efficient, cost effective and safe out-patient procedure in diagnosis of thyroid nodules. With the advent of Bethesda system of reporting thyroid FNAC, the procedure has obtained even more standardization, reproducibility, predictive value and all in all, greater clinical significance. Aim: The aim of this study was to assess the effectiveness of FNAC thyroid reported under Bethesda guidelines by comparing the preoperative cytological diagnoses with the postoperative histopathological diagnoses. Methods: In this study, FNAC of 768 patients of clinically palpable thyroid swelling were evaluated and classified according to the Bethesda system. 188 patients of this group underwent surgical management and histopathological diagnosis was obtained in them. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FNAC reported under Bethesda system were obtained by comparing the cytological and histopathological diagnoses. Results: The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FNAC came out to be 83.2%, 63.3%, 74.3%, 74.6% and 74.4% respectively. Conclusion: In our study, FNAC reported under Bethesda system came out to be a highly efficient tool in diagnosis of thyroid nodules. However, addition of more advanced methods like immunocytochemistry and molecular techniques can further increase this efficacy especially in the groups diagnosed as Atypia of undetermined significance/Follicular lesion of undetermined significance, Follicular neoplasm/Suspected for follicular neoplasm and Suspected for malignancy. Keywords: Thyroid, Bethesda System, FNAC, Histopathology