Figure 1a.

Thyroid metastasis from clear cell RCC in a 53-year-old man. (a) Coronal CT image of the chest with intravenous contrast material shows a heterogeneous nodule in the left lobe of the thyroid (yellow arrow). Note the subtle residual cortical irregularity in the right fifth rib (white arrow), which is a sequela of a metastasis that had been treated previously with stereotactic radiation therapy. (b) Coronal CT image of the chest from an examination performed 2 years later shows interval enlargement of the left thyroid lesion (yellow arrow). Again note the subtle cortical irregularity in the right fifth rib (white arrow). (c) Thyroid US image from an examination performed soon after the CT examination in b shows a predominantly solid nodule with scattered cystic components in the left thyroid lobe (arrows). Fine-needle-aspiration biopsy allowed confirmation of metastatic RCC.