Evaluating Thyroid Lesions Using Fine-Needle Aspiration Cytology and the Bethesda System: Insights From a Tertiary...

Introduction Thyroid enlargement is a common clinical condition often evaluated by various modalities, but fine-needle aspiration cytology (FNAC) remains the gold standard for accurate diagnosis and surgical decision-making. This study aimed to assess the cytological spectrum of thyroid lesions and evaluate the impact of FNAC in reducing unnecessary surgical interventions in a tertiary care center. Materials and methods A combined prospective and retrospective study was conducted on 282 patients with thyroid lesions at the All India Institute of Medical Sciences, Deoghar, Deoghar, Jharkhand, India, from August 2023 to March 2025. FNAC samples were classified according to the 2023 Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Clinical and cytomorphological data were analyzed to determine lesion distribution and malignancy risk. Results The majority of cases (85.1%) were benign (Bethesda category II), with colloid goiter (42.55%) and lymphocytic thyroiditis (28.01%) being most prevalent. Indeterminate (category III) and suspicious/malignant lesions (categories IV-VI) collectively accounted for approximately 15% of cases. No non-diagnostic samples were reported, attributed to on-site adequacy evaluation and ultrasound-guided aspirations. A significant association was observed between gender and cytological diagnosis (p=0.010), with lymphocytic thyroiditis being more common in females and suspicious papillary carcinoma more frequent in males. Confirmed papillary carcinoma constituted 1.8% of cases, comparable to previous studies. The Bethesda System effectively stratified malignancy risk, guiding appropriate clinical management. Conclusion FNAC is a cost-effective, minimally invasive tool that reliably distinguishes benign from malignant thyroid lesions, thereby reducing unnecessary surgeries. The Bethesda System standardizes reporting and enhances communication between clinicians and pathologists, supporting evidence-based management. Ultrasound guidance and strict adherence to adequacy criteria optimizes diagnostic yield, making FNAC indispensable in thyroid lesion evaluation.