Kim M, et al. - Experts assessed if tumor size and tumor growth rate could distinguish follicular thyroid carcinoma (FTC) from follicular adenoma (FA) in patients with pathologically proven FTCs and FAs who underwent preoperative serial neck ultrasonography (US) at least 3 times. Malignancy could not be predicted by the tumor size and growth rate of the thyroid nodule. For making the decision of diagnostic surgery for patients with follicular tumors, diagnostic approaches that use molecular markers would be more important than clinical features.