Decoding Thyroid Lesions – A Correlative Study Between Cytology and Radiological Findings

Abstract

Background: Thyroid nodules are among the most frequently encountered endocrine lesions, with the majority being benign while a small but significant proportion harbor malignancy. Accurate preoperative risk stratification is essential to avoid unnecessary surgical intervention and ensure timely management of malignant lesions. Fine-needle aspiration cytology (FNAC) and ultrasonography are widely used diagnostic tools, and their combined application may enhance diagnostic accuracy.

Objectives: To correlate cytological findings categorized according to the Bethesda System for Reporting Thyroid Cytopathology with ultrasonographic findings classified using the ACR TI-RADS system and to evaluate their diagnostic performance against histopathological examination.

Materials and Methods: This cross-sectional observational study included 261 patients with thyroid lesions who underwent FNAC, ultrasonographic evaluation, and subsequent surgical excision between January 2023 and December 2024. Cytological diagnoses were reported according to the Bethesda System, while ultrasonographic findings were categorized using ACR TI-RADS. Histopathological examination served as the gold standard. Sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy, and agreement between modalities were assessed.

Results: Of the 261 patients studied, females constituted 80.1% of cases, with the highest frequency observed in the 21–40-year age group. Bethesda category II lesions were the most common cytological diagnosis (67.4%), while TI-RADS category TR3 represented the largest radiological group (30.3%). FNAC demonstrated a sensitivity of 86.0%, specificity of 91.5%, and diagnostic accuracy of 89.3%. Ultrasonography showed a sensitivity of 82.4%, specificity of 88.7%, and accuracy of 86.2%. The combined use of FNAC and TI-RADS significantly improved diagnostic performance, achieving a sensitivity of 92.9%, specificity of 94.1%, and overall accuracy of 93.4%. Discordant findings were predominantly encountered in indeterminate cytological categories.

Conclusion: Integration of Bethesda-based cytological reporting with ACR TI-RADS risk stratification substantially improves the preoperative evaluation of thyroid nodules. The combined approach enhances diagnostic accuracy, facilitates more effective risk stratification, and supports informed clinical decision-making, thereby reducing unnecessary surgical procedures while ensuring appropriate management of malignant thyroid lesions.