Surgical outcomes of Bethesda System for Reporting Thyroid Cytopathology diagnostic category class I, II, and III thyroid nodules

초록

Objectives – According to the Bethesda System for Reporting Thyroid Cytopathology, surgery is recommended for Bethesda classes I–III thyroid nodules only in selected situations, such as large or growing tumors with compressive symptoms or clinical suspicion of malignancy. Clinical findings and cytopathologic evaluation are often considered together to reduce discrepancies between preoperative cytology and final pathology. This study aimed to evaluate surgical outcomes in Bethesda classes I–III nodules and to identify risk factors predictive of malignancy. Methods – In this retrospective review, we included patients who underwent thyroidectomy for thyroid nodules classified as Bethesda classes I–III based on preoperative US-guided fine-needle aspiration (FNA) between 2010 and 2020. We collected data including preoperative cytopathology and ultrasound findings to analyze the risk factors related to malignancy and to evaluate treatment outcomes. Results – Among 192 patients, carcinoma was confirmed in 62 (32.3%). The malignancy rates for Bethesda classes I, II, and III were 23.5%, 20.4%, and 49.4%, respectively. The malignant histologic types included papillary thyroid carcinoma (PTC; n = 34, 54.8%) and follicular thyroid carcinoma (FTC; n = 23, 37.1%), while five cases (8.1%) showed coexisting histologic types, including multiple PTC variants or a combination of minimally invasive FTC and PTC. Bethesda class III showed a significantly higher incidence of malignancy than the other classes (p < 0.001). In a subgroup analysis of class III nodules, larger nodule size on ultrasonography and atypia with both nuclear and architectural features (AUS-N/A) were associated with malignancy (p = 0.045 and p = 0.028, respectively). In a multivariate analysis, AUS-N/A was an independent predictor of malignancy (odds ratio 13.275, 95% confidence interval 1.354–130.3, p = 0.026). Conclusion – Bethesda class III nodules showed a higher risk of malignancy. Surgical intervention should be considered, particularly when AUS-N/A is identified in Bethesda class III nodules. Even in cases where carcinoma was confirmed after surgery for Bethesda classes I, II, and III, the probability of recurrence was very low and the prognosis is favorable. Copyright © 2026 Park, Lee, Kim, Kwon, Jung, Choi, Song and Lee.

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