Renal metastasis from Hurthle cell thyroid carcinoma and its evaluation with hybrid imaging.

BACKGROUND In general, thyroid carcinomas, when they behave aggressively, metastasize to lungs and occasionally to bone and brain. Metastases to other organs are distinctly unusual. Renal metastases have been reported in only 10 patients. Here we report, to the best of our knowledge, the first patient with Hurthle cell thyroid cancer and renal metastasis. The evaluation of this patient was enhanced by utilizing a variety of imaging techniques. SUMMARY The patient was a 75-year-old man who had a history of a total thyroidectomy 9 years previously for a right thyroid lobe Hurthle cell carcinoma. He postoperatively received 150 mCi (5550 MBq) of 131-I therapy and was maintained on thyrotropin suppressive therapy with levothyroxine. He presented to us with a recent history of a progressively enlarging left neck mass. The serum thyroglobulin was elevated to 1183 ng/mL. Multimodality imaging with fluorodeoxyglucose positron emission tomography-computed tomography, magnetic resonance imaging, and Somatostatin receptor scintigraphy with single photon emission computed tomography (SPECT)-computed tomography revealed numerous foci in the skeleton and right kidney. Anatomic imaging characteristics favored a primary renal cell cancer with the additional evidence of renal vein invasion and thrombosis. Histology later revealed a metastatic renal Hurthle cell cancer with positive thyroglobulin stains. Several of the skeletal foci responded partially to cryoablative therapy. The patient refused noncurative Somatostatin analog therapy. He is alive and doing well clinically. CONCLUSION The management of thyroid cancers in high-risk groups, such as our patient, frequently requires expert management by the use of novel multimodality imaging and therapeutic techniques.