The aim of this study was to investigate the value of ultrasound in diagnosis of benign and malignant thyroid nodules with rim calcification.

Sixty thyroid nodules with rim calcifications from Sun Yat-sen University Cancer center which were detected on ultrasound from January 2008 to December 2015 were included in this study, and all the thyroid nodules had pathological results. Ultrasonic features of thyroid nodules, including the size, border, internal echo, growth pattern, rear echo, interruption or inner sink of the rim calcification and hypoechoic soft tissue extrusion around rim calcification were analyzed.

Thirty-seven nodules (61.7%) were confirmed to be benign, and twenty-three nodules (38.3%) were malignant. The ultrasonic features of interruption or inner sink of rim calcifications and hypoechoic soft tissue extrusion around rim calcification, were more often in malignant nodules than benign nodules. The sensitivity, specificity, the positive predictive values and the negative predictive values for interruption or inner sink of rim calcifications were 85.7%, 89.4%, 85.7% and 89.4%, respectively. The sensitivity, specificity, the positive predictive values and the negative predictive values for hypoechoic soft tissue extrusion around rim calcification were 81.3%, 94.4%, 92.9% and 85.0%, respectively. Internal hypoechogenicity was more frequently observed in the malignant nodules (82.6%) than in benign nodules (40.5%). The longitudinal growth pattern of thyroid was more frequently observed in malignant nodules (30.4%) than in benign nodules (2.7%). The differences of this two ultrasound features were statistically significant (χ²=9.958 and 9.440, both P<0.01). There were no significant differences in size, border and the rear echo between malignant and benign nodules (all P>0.05).

The interruption or inner sink of the rim calcification could be useful in differential diagnosis of thyroid nodules with rim calcification.