Background: Fine Needle Aspiration Cytology (FNAC) is important for pre-operative and pre-treatment diagnosis of benign and malignant thyroid lesions, thus decreasing the incidence of unwanted surgeries. Objectives: The present study aims to classify various cytomorphological lesions of the thyroid according to The Bethesda System for Reporting of Thyroid Cytopathology(TBSRTC) and correlate these with histopathology so as to establish the utility of FNAC in the diagnosis of thyroid lesions. Material & Methods: A retrospective study was conducted in a tertiary care centre to evaluate the diagnostic accuracy of FNAC in lesions of thyroid during a 3 year period. The cytological findings were classified according to the recent TBSRTC and subsequent histopathological correlation was done in all the cases. Results: Out of total 200 cases studied, benign category (II) was the most common (79.0%) followed up by malignant (VI -11.0%) and follicular neoplasm (IV-9.0%) categories. Cyto-histopathologic correlation of all cases was done. The present study showed 92.85% sensitivity, 100% specificity, 100% positive predictive value, 98.8% negative predictive value and 99% diagnostic accuracy in detecting malignant tumors. Conclusions: FNAC is a safe, simple, highly accurate, economical and universally accepted modality for evaluation of thyroid lesions especially in developing countriessuch as India. Use of TBSRTC in reporting thyroid cytopathology has a greater accuracy. There is almost perfect cyto-histopathological concordance and the results are consistent with those available in the literature.

Keywords: Diagnostic Accuracy; FNAC; Histopathology Correlation; Sensitivity; Specificity; Thyroid.