We report a rare case of a solitary metachronus metastasis of renal clear cell carcinoma (RCC) in the thyroid coexisting with parathyroid tumors. The patient had undergone 20 years ago radical left nephrectomy for RCC. Upon presentation, the initial diagnosis based on clinical and echo findings was multinodular goiter. Fine needle aspiration (FNA) cytology of a growing non-functioning nodule of the right thyroid lobe revealed clear cells with oxyphilic granules suggesting RCC. Immunohistochemical studies showed the tumor cells to be negative for thyroglobulin staining. In addition immunostaining with keratin ae1ae3, epithelial membrane antigen, and vimentin gave positive results, confirming further the diagnosis of metastatic RCC in our case. The coexisting parathyroid tumors were assessed preoperatively by Tc-99m substraction scintigraphy, intraoperatively by monitoring parathyroid hormone and postoperatively by histology.
03 - 07 May 2008
European Society of Endocrinology