Thyroid metastases from clear cell renal cell carcinoma: A case report.

e15066 Background: Renal cell carcinoma can metastasize to unusual sites such as the thyroid gland. Such cases typically present with a unilateral painless cold nodule at scintiscan, hypoechogenic at ultrasonography, with final diagnosis made by fine-needle aspiration. Methods: An 87-year-old woman with clear cell renal cell carcinoma was treated by radical nefrectomy in April 2003. She relapsed in 2009 in the abdomen and underwent resection of the large, symptomatic metastasis. Around the same time bilateral lung lesions appeared. The patient was subsequently treated with sunitinib 50 mg daily in cycles of 4 weeks with a two-week interval. The dose was reduced to 37.5 mg because of bone marrow toxicity. After 17 months of treatment the lung metastases were stable but bilateral thyroid nodules were detected. Results: Thyroid function tests were normal. Ultrasound-guided biopsy found atypical cell aggregates with clear cytoplasm and positivity for CD10 and vimentin, compatible with clear cell renal cell ca...