Frozen Section as an Aftermath to Fine Needle Aspiration Cytology in Thyroid Lesions

Introduction: Study of thyroid diseases are of significant importance as it has implications on medical and surgical management. The choice of the diagnostic method used is also vital as it may influence the quality of the outcome. Fine Needle Aspiration Cytology (FNAC) has for long been a useful, cheap and safe procedure in preoperative evaluation of thyroid lesions. Frozen sections on the other hand can confirm the FNAC diagnosis and it also serves as an intraoperative guide to decide the extent of the thyroid surgeries. Aim: To assess the diagnostic accuracy of FNAC and frozen sections and to determine the utility of frozen sections in thyroid lesions. Materials and Methods: This five year retrospective study was conducted between July 2010 to July 2015. All patients undergoing both FNAC and frozen sections for thyroid lesions were included in the study. Results were then compared with the gold standard which is histopathology. SPSS 20.0 software was used to analyse the data. Descriptive statistics was applied to draw conclusions. Sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and diagnostic accuracy were calculated for both FNAC and frozen sections. Results: Among 70 cases, FNAC was reported as nonneoplastic in 43 cases among which eight cases differed on histopathology. Total 27 cases reported as neoplastic of which eight cases differed on histopathology. On frozen sections, among 43 reported as non neoplastic and 27 as neoplastic, only four cases in each differed on histopathology studies. On the final histopathology sections 43 were non neoplastic and 27 were neoplastic lesions (9 benign, 18 malignant). FNAC sensitivity was 70.37%, specificity was 81.39%. Frozen section sensitivity was 85.18%, specificity was 90.69%. The difference was statistically significant. Conclusion: In the present study, frozen sections had better sensitivity and specificity compared to FNAC in thyroid lesions. Thus, concluding that FNAC can definitely help the clinician to stratify the patients and select them for surgery but frozen section can confirm the FNAC diagnosis and guide the extent of thyroidectomy.