Predictive factors of malignancy in follicular thyroid nodules (THY3): Our experience on 324 patients

Aim. Aim of the present retrospective study is the identification of the best management strategy for nodules with Thy3 cytology and to identify risk factors of malignancy correlating the clinical and sonographic data with the malignancy rates. Methods. 324 cases with indeterminate nodules (Thy3) were included in this study. 257 were female (79.3%) and 67 male (20.7%), with a mean age of 50.41 ± 14.26 years. All patients underwent total thyroidectomy. Results. Malignancy was diagnosed in 113/324 patients (34.87%); thyroiditis coexisted in 146/324 (45.06%) and was associated with cancer in 44 (44/113; 38.94%). Of the sonographic characteristics, 68/211 benign lesions (32.22%) and 71/113 malignant were hypoechoic (62.83%),19/211 (9%) benign and 74/113 malignant (65.48%) had irregular margins; these data were statistically significant. None of the clinical features, nor the presence of microcalcifications or type 3 vascularization were significantly associated with malignancy. Conclusion. The risk of malignancy in cytologically indeterminate thyroid lesions was high in the present study and, in a significant number of cases, Hashimoto's thyroiditis and hyperplastic nodular goiter were associated. Clinical features were inaccurate predictors of malignancy, and of the sonographic features only hypoechoic appearance and irregular margins were highly predictive of malignancy. We recommend surgery in the treatment of Thy3 and we prefer total thyroidectomy for the high incidence of malignancy, the unreliability of intraoperative frozen section examination, and the frequency of multiple lesions, hyperplastic nodular goiter, or thyroiditis. Further research is needed to identify predictors of malignancy in indeterminate nodules in order to avoid unnecessary procedures.