TIRADS classification and histopathological correlation in thyroidectomy cases: how accurate is the risk stratification?

Objectives: Thyroid nodules, although frequently benign, carry a malignancy risk in approximately 8–16% of cases. The use of structured classification systems such as TIRADS and cytological evaluation via fine needle aspiration biopsy (FNAB) help guide clinical decision-making and avoid unnecessary surgery. This study aimed to evaluate the sensitivity, specificity, and diagnostic accuracy of TIRADS classification and FNAB in predicting malignancy in thyroid nodules and to assess their correlation with final histopathological outcomes after thyroidectomy. Methods: A retrospective analysis was conducted on 489 patients who underwent thyroidectomy between January 2016 and July 2020, in accordance with ATA guidelines. Data collected included demographic features, comorbidities, ultrasound-based TIRADS classifications, FNAB results (Bethesda classification), preoperative and postoperative biochemical parameters, and final histopathological diagnoses. Results: Malignancy was detected in 9.48% of cases. The mean age of malignant cases was 48.8 years. FNAB showed a sensitivity of 50%, specificity of 98%, negative predictive value of 87.4%, and positive predictive value of 88.5%. Among nodules categorized as “suspicious for malignancy” by FNAB, 51.4% were confirmed as malignant on final pathology. The malignancy rates according to TIRADS scores 1 to 5 were 7.1%, 20.3%, 27.1%, 37.1%, and 57.1%, respectively. When only malignant and suspicious-for-malignancy FNAB results were considered positive, the malignancy risk was 33.6% for TIRADS 4 and 83.3% for TIRADS 5 nodules. Conclusion: This study revealed notable malignancy rates even in TIRADS 1 and 2 nodules, which are generally considered benign in current guidelines. TIRADS categories 4 and 5 showed statistically significant correlations with malignancy, reinforcing their utility in preoperative risk stratification.