Improving Diagnostic Performance for Thyroid Nodules Classified as Bethesda Category III or IV: How and by Whom Ultrasonography Should be Performed

Background: The purpose of this prospective study is to evaluate if the association of Bethesda system and a 3-categories Ultrasonography (US) risk stratification system proposed by the American Association of Clinical Endocrinologists/American College of Endocrinology/Associazione Medici Endocrinologi improves the performance of cytology alone in III or IV categories and if further variables such as US provider (radiologist; endocrinologist, or endocrine surgeon both coming from a dedicated team) influence the accuracy of the diagnostic. Methods: 570 consecutive patients with complete clinical records, affected by Bethesda III or IV nodules, have been addressed to two public referral surgical centers of Western Sicily. Age, sex, autoimmunity, nodule size, and US provider were recorded. Fisher's exact test was used for the univariate analysis; Odd's ratios were calculated for the multivariate analysis. Results: 248 patients had malignancy at histology, 322 were benign. The mean age was 52 years for the malignancy group and 58 y for the benign group (P < 0.001). At univariate analysis, autoimmunity was correlated with benign group (P < 0.001), and US risk 2 and 3 were correlated with malignancy (nearly 10-folds, P < 0.001); In addition, no difference was found concerning nodule size. At multivariate analysis, US risk 2 and 3 were strong predictors of malignancy (P < 0.0001) especially if cytology was Bethesda IV; endocrinologist and surgeon were more accurate in predicting malignancy compared with the radiologist (P < 0.01). Conclusions: In the context of indeterminate nodules, the American College of Endocrinology/American Association of Clinical Endocrinologists/Associazione Medici Endocrinologi US risk stratification system strongly improves the results of Bethesda system especially when performed from dedicated endocrinologist or endocrine surgeon.