Comparison between Fine Needle Aspiration Cytology with Histopathology in the Diagnosis of Thyroid Nodules

Abstract

Background: Accurate diagnosis of thyroid nodules is crucial for avoiding unnecessary surgeries and enabling timely treatment. Fine needle aspiration cytology (FNAC) and ultrasound are commonly employed diagnostic techniques, but their reliability is debated. This study aimed to compare the diagnostic accuracy of FNAC and ultrasounds using histopathology as the reference standard. Methods: A retrospective review was conducted on 344 patients who underwent thyroidectomy between January 2017 and May 2022. An ultrasound and FNAC were performed before surgery, and histopathological findings were compared. Statistical analyses were conducted to calculate sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false positive rate, false negative rate, and overall accuracy for each diagnostic method. Results: Among the study population, 38.67% of thyroid tumors were malignant. Ultrasound showed a sensitivity of 68.18%, specificity of 76.55%, PPV of 64.74%, NPV of 79.20%, and overall accuracy of 73.31%. FNAC had a sensitivity of 89.31%, specificity of 48.44%, PPV of 78%, NPV of 68.89%, and accuracy of 75.89%. The correlation coefficient between ultrasound and FNAC was 0.512 (p < 0.0000001). Ultrasound correlated with histopathology with a coefficient of 0.408 (p < 0.0000001), while FNAC with histopathology had a coefficient of 0.304 (p < 0.00001). The correlation coefficient between these three diagnostic methods was 0.423 (p < 0.0001). Conclusion: In the diagnosis of thyroid nodules, both FNAC and ultrasound demonstrated moderate diagnostic accuracy. Ultrasound showed a higher specificity, while FNAC exhibited a higher sensitivity. Combining these techniques may improve diagnostic accuracy. Further research and the development of more reliable diagnostic methods are warranted to optimize the management of thyroid nodules and avoid unnecessary surgeries.