Papillary thyroid carcinoma with clear cell renal cell carcinoma metastasized to the thyroid gland: A case report.

Metastasis of clear cell renal cell carcinoma (ccRCC) to the thyroid gland is rare, and simultaneous occurrence of ccRCC and papillary thyroid carcinoma (PTC) is even rarer. Due to the occult nature of the disease, the clinical diagnosis is difficult. In the case of multiple tumors, the possibility of thyroid metastasis should not be ignored during the clinical diagnosis and treatment of PTC. The present study reported a case with initial diagnosis of PTC and accidental discovery of thyroid metastasis of ccRCC. This case study aims to improve the understanding of occult thyroid metastasis, providing a reference for its clinical diagnosis and treatment. Accordingly, misdiagnosis and missed diagnosis of this disease may be reduced and the survival rate and the life quality of patients can be improved.