Follicular Adenoma and Follicular Thyroid Carcinoma

Abstract

A follicular tumor is often solitary. It often has an egg shape, is well marginated, and has a hypoechoic halo all around the tumor [5,6,10]. Most follicular tumors are solid and have homogeneous echogenicity. They can be hyper-, iso-, hypoechoic, or mixed with well-defined areas of different echogenicity within the tumor. Focal cystic components may be present. They usually have a “spoke-and-wheel-like” vascularity with marked circulation in the peripheral halo with vessels converting toward the tumor center. In our experience carcinomas have a tendency to have more rich and less regular flow in the periphery and inside the tumor compared with the flow in the adenomas. A thick and uneven halo is suspicious for malignancy, and if extrathyroidal infiltration is visualized, the carcinoma diagnosis is obvious.