Long-Term Ultrasonography Follow-Up of Thyroid Colloid Cysts at the Health Center: A Single-Center Study

Objective. No previous study has employed long-term follow-up ultrasonography (US) examinations for evaluating thyroid colloid cysts (TCCs) in the general population. This study aimed to assess the interval changes of TCCs at the health center by evaluating long-term US follow-up examinations. Methods. For evaluation of the thyroid gland at our health center from 2006 to 2010, 3692 individuals underwent 4 or more thyroid US examinations at an interval of 1 year or 2 years. We assessed the interval changes of TCCs >= 5 mm on US follow-up examinations. Results. Of the 3692 subjects, only 115 (3.1%) showed TCCs >= 5 mm on one or more thyroid US examinations. The interval changes in TCCs, as shown by the thyroid US examinations performed during the study period, were classified as follows: no interval change (n = 60), gradual increase (n = 37), gradual decrease (n = 6), positive fluctuation (n = 10), negative fluctuation (n = 0), and disappearance (n = 2). No subject reported any relevant symptom pertaining to TCCs. Conclusions. Overall, follow-up US examinations showed various interval changes in TCCs, but a majority of TCCs showed no interval change or a gradual increase in size.