Letter: natural course of cytologically benign thyroid nodules: observation of ultrasonographic changes (endocrinol metab 2013;28:110-8, dong jun lim et Al.).

With increased health screening and the development of high-resolution ultrasound (US) techniques, thyroid nodules are commonly seen in clinical practice. When a patient presents with a thyroid nodule, the primary concern is whether it is benign or malignant. After ruling out malignancy with fine needle aspiration (FNA), which is typically performed with ultrasonographic guidance, the next concern is appropriate follow-up [1]. Although diagnostic strategies for detecting malignant nodules have been intensively investigated, follow-up strategies for benign thyroid nodules remain unclear.

Lim et al. [2] demonstrated the natural course of benign thyroid nodules by investigating a total of 202 nodules over a mean follow-up period of 22 months. Of these, 20.8% showed changes on US: nodule volume increased in 11.8% and decreased in 8.3%. Specific US findings or the number of FNAs could not predict increases in nodule volume; however, younger diagnostic age was significantly associated with it. Based on these data, the authors concluded that frequent follow-up should be considered in only a small number of cases with suspicious US findings, and that, in particular, frequent re-evaluation with US is rarely needed in elderly patients. This is a valuable finding in terms of developing an appropriate follow-up strategy for benign thyroid nodules. An additional interesting finding of this study was the impact of frequent FNA on the size or morphologic change of thyroid nodules. There is an on-going debate about whether frequent FNA changes the texture of thyroid nodules [3]; Lim et al. [2] demonstrated that FNA partially changed the cystic nature of nodules, but did not affect their size, suggesting that the procedure has minimal impacts on thyroid nodules [2].

Since socioeconomic budgets for managing thyroid nodules have grown with corresponding increases in the clinical detection of nodules, establishing an evidence-based follow-up strategy for benign thyroid nodules is an urgent task in this field. Further large-scaled prospective studies on this topic are needed.