A 19-year-old female underwent two radiofrequency ablation procedures for a thyroid tumor that was proven to be nodular hyperplasia versus a follicular neoplasm by fine-needle aspiration. Two years after the last follow-up, the thyroid mass had grown and a newly developed mass was detected in the platysma muscle. After surgery, the thyroid mass was revealed to be a solid papillary thyroid carcinoma, and the subplatysmal mass was tumor seeding.