Peripheral Calcification in Thyroid Nodules: Ultrasonographic Features and Prediction of Malignancy

The purpose of this study was to investigate the association between peripheral calcification in thyroid nodules detected on ultrasonography and thyroid malignancy. We retrospectively analyzed the ultrasonographic features of 65 pathologically proven thyroid lesions showing peripheral calcification for their correlation with histopathologic results. The following ultrasonographic parameters were assessed for each nodule: size (maximal dimension), shape (anteroposterior dimension/transverse dimension ratio), internal echogenicity (hypoechoic, isoechoic, hyperechoic, or invisible), halo sign (present or absent), type of calcification (stippled, curvilinear/smooth margin, or curvilinear/irregular margin), and extent of calcification (arc or rim). Twelve (18.5%) of 65 thyroid nodules with peripheral calcification were malignant, and 53 (81.5%) were benign. Patient demographics (age and sex) and ultrasonographic features of the nodules (size, shape, internal echogenicity, halo sign, and type and extent of calcification) did not show any significant differences between benign and malignant groups. The relatively high prevalence of malignancy and no reliable criterion for malignancy in thyroid nodules with peripheral calcification indicate that fine-needle aspiration or careful ultrasonographic follow-up may be warranted in these cases.