Background: The risk of malignancy from nodules with atypia of undetermined significance cytology is estimated between 5% and 15%, though more recent studies suggest rates upwards of 48%. This study sought to characterize preoperative predictors of malignancy to aid in clinical decision-making.
Methods: We performed a single institution retrospective review of all adult patients with unilateral thyroid nodules demonstrating atypia of undetermined significance cytology between March 1, 2013 and June 1, 2019 who underwent surgical resection (n = 266). Univariate and multivariate logistical analysis was performed using clinical and demographic variables to identify potential preoperative characteristics associated with malignant disease.
Results: Malignancy was identified on final pathology in 24.7% of patients with atypia of undetermined significance cytology. Age, sex, exposure to ionizing radiation, family history of thyroid cancer, Hashimoto's disease, Afirma suspicious results, and smoking were not associated with malignancy on both univariate and multivariate analysis. Nodule size >4 cm was independently associated with malignancy risk on both univariate (odds ratio 2.44, 1.09-5.43, P < .03) and multivariate (odds ratio 2.96, 1.27-6.87, P < .02) analysis.
Conclusion: The results of this study demonstrate that nodules with atypia of undetermined significance cytology >4 cm are strongly associated with malignancy. We recommend strong consideration of surgery for all patients with thyroid nodules >4 cm and atypia of undetermined significance cytology.
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