Metastatic renal clear cell carcinoma in the thyroid gland diagnosed by fine needle aspiration cytology.

An 81-year-old woman presented with a mass in the right lobe of the thyroid. Fine needle aspiration of this lesion showed metastatic clear cell carcinoma. This was subsequently confirmed histologically. In patients with metastatic carcinoma, tumour deposits are frequently found in the thyroid. The most common metastatic tumour to masquerade as a primary thyroid tumour is a renal cell carcinoma. In patients with this tumour the possibility that a thyroid mass may be a metastatic deposit should always be considered.