Metastatic Clear Renal-Cell Carcinoma Mimicking Anaplastic Thyroid Cancer: A Case Report.

Metastatic renal cell carcinoma to the thyroid is a rare yet aggressive histopathologic diagnosis, which may often be omitted from the initial clinical differential. This is in part due to the long latency period between the initial renal primary and appearance of metastatic disease, coupled with the diagnostic limitations of fine-needle aspiration biopsies. We herein present an interesting case of a metastatic clear-cell renal-cell carcinoma mimicking an aggressive primary thyroid neoplasm, 10 years after a nephrectomy for a renal primary, highlighting key diagnostic and management considerations.