A Prospective Study on 3, 907 Patients with Thyroid Nodules. Sono-histological Comparison and the Controversial Significance of the Halo Sign in Predicting Thyroid Malignancy.

ABSTRACT

Background: The aim of this study was a comparison of the ultrasonographic (US) and histopathological findings on patients with thyroid nodules (TNs) in a moderately iodine-deficient region. Methods: The US properties (The echostructure, the presence of halo sign, microcalcification, blurred border, vascularization, and the taller-than-wide sign) of 7,180 TNs were assessed in 3,907 patients later underwent surgery. Results: 411 malignant cases were found. The risk of malignancy was significantly higher in cases involving a hypoechogenic nodule, microcalcification, a blurred border, type 3 vascular pattern or the taller-than-wide sign. The presence of a halo sign was associated with a significantly lower risk of malignancy in cases with hypoechogenic TNs, but with a significantly higher risk in cases with moderately hypoechogenic TNs. As concerns hyperechogenic TNs, the presence of a halo sign had no influence on the risk of malignancy. Among the patients with microfollicular proliferation without atypia on cytology, the risk of malignancy was significantly lower in the absence than in the presence of a halo sign. Conclusions: The US features of a malignant TN are in general the same in our iodine-deficient region as in iodine-sufficient areas. The significance of a halo sign depends considerably on the echostructure of the TN. A combined assessment of the US and cytological findings may help avoid unnecessary surgery in patients with suspected follicular tumor.