Evaluation of Thyroid Lesions by Fine-needle Aspiration Cytology According to Bethesda System and its Histopathological Correlation

BACKGROUND: The Bethesda system is a uniform reporting system for thyroid cytology that facilitates the clarity of communication among cytopathologists, radiologists, and surgeons and facilitates cytohistologic correlation for thyroid diseases. OBJECTIVE: This study was carried out to evaluate thyroid lesions by fine-needle aspiration cytology (FNAC) based on Bethesda system of reporting and to correlate the cytological findings with histopathology. MATERIALS AND METHODS: A total of 606 patients with thyroid lesions were studied by FNAC at our institute between January 1, 2006, and January 31, 2016, and results were compared with histopathology wherever possible. RESULTS: Based on the Bethesda system of classification of thyroid lesions, out of 580 satisfactory samples; 501 lesions were diagnosed as benign (Group 1), five were in category of atypical follicular lesion of atypia undetermined significance (Group 2), 55 were diagnosed as suspicious for follicular neoplasm (Group 3), 7 as suspicious for malignancy (Group 4), and 12 cases were malignant (Group 5). 26 aspirates were nondiagnostic even after reaspiration. In the present study, cytohistopathological correlation was done in 148 benign and 18 malignant lesions. The sensitivity of FNAC was 85.7%, specificity 98.6%, and diagnostic accuracy 97.7%. CONCLUSION: Reviewing the thyroid FNAs with the Bethesda system for reporting allowed precise cytological diagnosis. It represents standardization and reproducibility in reporting thyroid cytology with improved clinical significance and greater predictive value. Nature of the disease, experience of cytopathologist, and understanding of certain limitations determine its diagnostic utility.