Hyperplastic nodule is characterized by the presence of colloid, fibrovascular structures, a relatively high ratio of monolayered sheets and isolated cells to isolated follicles, and a moderate degree of anisonucleosis. In contrast with the non-tumorous lesion, follicular tumor presents no colloid, predominance of follicles, a minimal degree of anisonucleosis and presence of prominent nucleoli.

The ultrasound presentations are less typical. There was a large solitary nodule occupying almost the entire lobe in the hyperplastic case. The presence of a halo is doubtful while the lesion lacks perinodular blood flow. As regards the right patient, there were multiple nodules in the thyroid. The largest one was aspirated and proved to be a follicular adenoma. The lesion is surrounded with a hyperechogenic rim not displaying dorsal acoustic shadow. It is a rare presentation of a capsule because a capsule presents in most cases either as a hypoechogenic rim or a coarse calcification.