To assess the application value of ultrasound in the follow-up of thyroid cystic-solid nodules.

A retrospective analysis was performed 79 patients with cystic-solid nodules of the thyroid capsule who underwent ultrasound examination at Shanghai Ruijin Rehabilitation Hospital from November 2017 to June 2019. All the cystic-solid nodules were confirmed as benign nodules by cytological pathology. Among the patients included, 74 were selected for chemical ablation and physical ablation, 1 for drug therapy, and 4 for self-absorption. All patients were followed by ultrasound to observe the size, shape, boundary, internal echo, calcification, and blood flow signal characteristics of the nodules after absorption. The nodule size was recorded and compared with that before the absorption.

The 79 cases of thyroid cystic-solid nodules were characterized by different degrees of absorption in ultrasound follow-up. Nodule absorption occurred in the same area, characterized by low or very low echo nodules. Cystic components decreased gradually, even disappeared, and significantly decreased in volume. The average volume at the last follow-up was significantly smaller than that at the initial examination [(1.42±1.36) ml vs (40.78±34.01) ml, P=0.02]. The maximum reduction rate of nodule volume was 87%, the minimum reduction rate was 68%, and the average reduction rate was (75±5)%. Of the 79 nodules after absorption, 74 showed sonographic characteristics of malignant nodules and 5 did not.

Ultrasonic follow-up allows to dynamically observe the nodularity process. Thyroid cystic-solid nodules often show characteristics of malignant nodules during ultrasonic follow-up, and a clear understanding medical history may provide an important basis for determining "mummy nodules" to avoid excessive diagnosis and unnecessary cytological examination.