THE EFFECTIVENESS OF FINE NEEDLE ASPIRATION CYTOLOGY IN DIAGNOSING THYROID SWELLINGS AND THE REASONS FOR DISCREPANCIES: A 6-YEAR CYTOHISTOLOGIC CORRELATION STUDY

Abstract

Background: FNAC is a safe, reliable, cost-effective, and efficient method for initial screening  of patients with thyroid nodules.
Aims: The purpose of this study was to evaluate the diagnostic efficacy of FNAC as a screening tool for thyroid nodules, identify cytomorphological features that contribute to diagnostic errors, and suggest improvements.
Materials and Methods: A study included 611 cases of FNAC, with 99 cases being compared to histological diagnosis. Subsequently, discordant cases, including both false negatives and false positives, were retrospectively re-evaluated. Additionally, a thorough review of previous research on the factors that contribute to misdiagnosis was conducted.
Results: When BSRTC categories IV, V, and VI are all classified as cytologically positive, the sensitivity, specificity, PPV, NPV, and diagnostic accuracy are 84.6%, 97.1%, 93.4%, 86.7%, and 91.9%, respectively. The primary reason for false-negative diagnoses was sampling errors (4/5, 80%), while the majority of false-positive diagnoses were attributed to interpretation errors (1/3, 33.3%). Overlapping cytological features in adenomatoid hyperplasia, thyroiditis, and cystic lesions were the primary factors contributing to misinterpretation. Additionally, heterogeneity and unsampled areas were responsible for variations in nodule size and number.
This may have resulted in a false negative diagnosis Conclusion: The results of our study have demonstrated that FNAC of thyroid lesions exhibits a significant level of accuracy, sensitivity, and specificity, enabling appropriate initial diagnostic intervention. Cytopathologists should improve their criteria for identifying adenomatous hyperplasia, thyroiditis, and cystic lesions in order to avoid false-positive diagnoses caused by errors in interpretation.