RID49884 halo

definition [TIRADS]: Border consists of a dark rim around the periphery of the nodule. The halo can be described as completely or partially encircling the nodule. In the literature, halos have been further characterized as uniformly thin, uniformly thick, or irregular in thickness.

comment A halo may be due to a true fibrous capsule or a pseudocapsule. A uniform halo suggests a benign nodule because most thyroid malignancies are unencapsulated. However, a complete or incomplete halo has been noted in 10% to 24% of thyroid carcinomas.