Simultaneous Uptake of I-131 and F-18 FDG by a Renal Metastasis of Thyroid Papillary Cancer

Renal metastasis of thyroid papillary cancer is rare and only a few cases have been reported. Most metastases of well-differentiated thyroid cancer alternatively accumulate either I-131 or F-18 fluorodeoxyglucose (FDG), according to tumor differentiation, and only a few metastases exhibit simultaneous I-131 and F-18 FDG uptake. This study shows the simultaneous I-131 and F-18 FDG uptake of metastatic renal mass in a patient with a 10-year history of thyroid papillary cancer. In our knowledge, this is the first report of thyroid cancer with renal metastasis as imaged by both I-131 SPECT/CT and F-18 FDG PET/CT.