Partially cystic thyroid nodules on ultrasound: The associated factors for malignancy

To identify the associated factors for malignancy in partially cystic thyroid nodules (PCTNs) on ultrasound (US).

This is a retrospective study. 338 PCTNs confirmed by surgery was included in this study. The US features of the nodules were reviewed and their significance in differential diagnosis was analyzed.

In the 338 PCTNs, 50 were malignant and 288 were benign. Univariate analyses revealed that a taller-than-wide shape and spiculated or microlobulated margin were significantly associated with malignancy while the spongy form, an ovoid to round shape and smooth margin were significantly associated with benign nature. In terms of the internal solid portion of the nodule, eccentric configuration, non-smooth margin, hypoechogenicity, and microcalcification were more frequently demonstrated in malignant nodules than in benign ones. In the multivariate logistic regression analysis, a taller than wide shape (OR: 13.357; 95% CIs: 3.457-28.797) was revealed to be the strongest independent predictor for malignancy, followed by microcalcification (OR: 11.578; 95% CIs: 3.142-29.563), spiculated or microlobulated margin (OR: 6.331; 95% CIs: 1.425-9.457), eccentric configuration (OR: 5.456; 95% CIs: 1.358-8.774), non-smooth rim of the internal solid portion (OR: 4.897; 95% CIs: 0.754-7.021), and hypoechogenicity of the internal solid portion (OR: 4.651; 95% CIs: 0.712-8.245).

Understanding the ultrasound characteristics of malignant PCTNs is important to make a precise diagnosis of thyroid nodules.