[Metastasis of thyroid carcinoma. A rare case of secondary renal tumor].

Secondary tumours of the kidney are becoming an increasingly frequent pathology due to the accurate follow-up and longer survival of cancer patients. The paper reports a rare case of renal metastasis from a thyroid carcinoma, which started as a Hürthle cell adenoma and was transformed into a carcinoma with a follicular appearance after 26 years. The suspicion of a secondary site was based on the high serum levels of HTG (human thyroglobulin); metastasis was identified following scintigraphic tests using a dual marker (99mTC, 201TL) and renal scintigraphy with 123I Hippuran. The definitive diagnosis was obtained following histological tests; conservative surgery was performed to treat the metastasis (tumorectomy with removal of healthy pericapsular tissue).