Long-term ultrasound follow-up of thyroid colloid cysts

Objective. This study aimed to assess the interval changes of thyroid colloid cysts (TCCs) by performing long-term ultrasound (US) follow-up examinations. Methods. From 2007 to 2008, 437 patients underwent a lobectomy for the treatment of papillary thyroid microcarcinoma. Among them, 268 patients underwent 4 or more postoperative US follow-ups after surgery. This study investigated the prevalence and interval changes of TCCs ≥3 mm by using US follow-ups. Results. Among 268 patients, 35 (13.1%) had TCCs ≥3 mm by a preoperative thyroid US, and 6 (2.2%) had newly detected TCCs at a US follow-up. Through long-term US follow-up, the interval changes for TCCs were classified as follows: no interval change (n = 8), gradual increase (n = 8), gradual decrease (n = 5), positive fluctuation (n = 3), negative fluctuation (n = 6), disappearance (n = 5), and new detection (n = 6). None of the TCC cases had a TCC that was ≥10 mm at its largest diameter, and no patient complained of any relevant symptoms pertaining to the TCCs. Conclusions. In this study, TCCs demonstrated various interval changes, but no abrupt increase was found or acute onset of symptoms occurred.