Papillary carcinomas - Figure 23. Sonographic signs - encapsulated form of papillary carcinoma.

This presentation is not the characteristic one and therefore may cause differential diagnostic problems. Although the presence of a halo sign suggests a significantly decreased risk of malignancy overall, the consequences of a detailed analysis indicate that the situation is not so simple. The absence of a halo decreases the risk of malignancy only because this sign cannot be demonstrated in the most frequently occurring malignant nodules, in hypoechogenic ones. The first 2 cases demonstrates this situation.