Should we reconsider high-risk features in thyroid ultrasonography?

Round shape is generally considered to reduce the risk of malignancy according to recent guidelines. On the contrary, according to some reports, spherically shaped thyroid nodules are associated with a higher risk of malignancy. Thus, we aimed to evaluate the malignancy risk of solid round isoechoic nodules detected at thyroid ultrasonography and compare it with that of solid ovoid isoechoic nodules.

Between 2017 and 2022, solitary solid round isoechoic nodules with diameters ³10 and £25 mm at thyroid ultrasonography were retrospectively selected and enrolled in the study. Age, size, nodule volume, serum thyrotropin levels, thyroid antibody levels, and cytopathological and histopathological results were recorded.

A total of 457 solitary solid isoechoechoic nodules from 457 patients (262 females and 195 males; median age, 59 [31-70] years) were selected, of which 203 were solid round isoechoic nodules, and 254 were solid ovoid isoechoic nodules. A total of 54 surgical operations were performed on 457 nodules, and 31 of them resulted in malignancy. From the 31 malignant results, 25 originated from solid round isoechoic nodules and the remaining 6 originated from solid ovoid isoechoic nodules (p<0.025).

We found that round nodules have higher malignancy rates than ovoid nodules. We think that ultrasonographic risk stratification systems used to target the most suitable nodules for the necessary biopsies can be dynamically updated, and sphericity can be added as a parameter in patient-based decision-making.