This Japanese study of 10 patients over 15 years, assesses the role of ultrasonography in assessing metastatic disease to the thyroid gland, specifically renal clear cell carcinoma (RCCC). Whilst uncommon, the authors state that there is a favourable prognosis when RCCC is confined to the thyroid gland and is amenable to surgery. They used five assessment markers when evaluating thyroid glands with ultrasonography, and found that RCCC formed one or two well demarcated lesions within the thyroid gland and was not diffusely involved. With two patients, postoperative histological analysis identified previously unknown RCCC arising from the kidney. Ultrasonography was used in conjunction with fine needle aspiration cytology (FNAC), with false negatives reported in four out of 10 patients. The authors recommended in their discussion for thyroglobulin levels to be analysed in FNAC washouts to help determine primary thyroid clear cell disease or disease arising elsewhere. Their conclusion was that preoperative assessment of these patients’ thyroid glands was useful and correlated well with postoperative histological analysis.