Abstract / Summary
Abstract Objective Although Bethesda II benign thyroid cytology is generally associated with a low risk of malignancy, false-negative results may occur in a subset of patients. Examining clinical, laboratory and ultrasonographic characteristics may help characterize patients with malignancy despite benign cytology. This study aimed to evaluate factors associated with postoperative malignancy in surgically treated patients with preoperative Bethesda II thyroid cytology. Materials and methods This retrospective single-center study included patients who underwent thyroid surgery following a preoperative Bethesda II fine-needle aspiration biopsy result between January 2020 and December 2024. Demographic characteristics, thyroid function tests, inflammatory markers and ultrasonographic findings were retrospectively analyzed. EU-TIRADS classification was categorized as low risk (< 4) and high risk (≥ 4). Patients were divided into benign and malignant groups according to postoperative histopathological results. Univariable and multivariable logistic regression analyses were performed to evaluate factors associated with postoperative malignancy. Results A total of 176 patients with Bethesda II cytology were included in the study. Postoperative histopathological examination revealed malignancy in 20 patients (11.4%). Patients in the postoperative malignant group were significantly younger than those in the benign group [29 years (IQR: 26.75–32) vs. 41 years (IQR: 35–49), p = 0.0006]. The rate of EU-TIRADS ≥ 4 was significantly higher in the malignant group (45.0% vs. 12.2%, p = 0.001). The malignancy rate was 7.4% in patients with EU-TIRADS < 4 and 32.1% in those with EU-TIRADS ≥ 4. In multivariable logistic regression analysis, younger age (OR: 0.918, 95% CI: 0.868–0.970, p = 0.002) and EU-TIRADS ≥ 4 classification (OR: 5.72, 95% CI: 2.01–16.27, p = 0.001) were independently associated with postoperative malignancy. Inflammatory markers such as neutrophil-to-lymphocyte ratio, systemic immune-inflammation index and C-reactive protein were not significantly associated with malignancy. Conclusion Younger age and EU-TIRADS ≥ 4 were associated with postoperative malignancy in this selected surgical cohort of patients with Bethesda II cytology. No statistically significant associations were observed for systemic inflammatory markers. These findings require confirmation in larger, prospective multicenter cohorts before their potential contribution to clinical risk assessment can be established.