Metastatic Renal Cell Carcinoma to the Thyroid Gland: A Case Report and Brief Review of the Literature

Renal cell metastasis to the thyroid gland: An emerging phenomenon

“…The thyroid gland is highly vascularised and on this basis one would expect it to be a common site for metastases [ [4] , [5] , [6] , [7] ]. Paradoxically, however, metastases only account for 1–3% of all thyroid malignancies [ [1] , [2] , [3] , [4] , [5] , [6] ]. Protective factors against metastatic deposits in the thyroid gland are thought to be its high concentration of oxygen and iodine, and the filtering capability of pulmonary capillaries [ 3 , 6 ].…”

“…Paradoxically, however, metastases only account for 1–3% of all thyroid malignancies [ [1] , [2] , [3] , [4] , [5] , [6] ]. Protective factors against metastatic deposits in the thyroid gland are thought to be its high concentration of oxygen and iodine, and the filtering capability of pulmonary capillaries [ 3 , 6 ]. Autopsy studies have suggested that the commonest primary sources of thyroid metastases are melanoma (39%) and breast carcinoma (21%) [ 3 , 6 , 7 ].…”

“…Protective factors against metastatic deposits in the thyroid gland are thought to be its high concentration of oxygen and iodine, and the filtering capability of pulmonary capillaries [ 3 , 6 ]. Autopsy studies have suggested that the commonest primary sources of thyroid metastases are melanoma (39%) and breast carcinoma (21%) [ 3 , 6 , 7 ]. However, a more recent review of clinical cases suggests that renal cell carcinoma now predominates as the leading cause of metastases from non-thyroid malignancies to the thyroid gland (48.1%) [ 1 , 2 , 5 ].…”

“…Intra-thyroid metastases are a rare occurrence, and account for 1–3% of all thyroid malignancies [ [1] , [2] , [3] , [4] , [5] , [6] ]. Previous research characterized melanoma and breast carcinoma as the commonest primary lesions leading to thyroid metastases, but more recent studies demonstrate that renal cell carcinoma (RCC) is now the most prevalent [ [1] , [2] , [3] , 6 , 7 ]. The advent of CT scans has led to increased incidental detection rates for renal cell carcinoma [ 8 ].…”

“…Typically, primary renal cell carcinoma is treated with surgical resection as the tumour tends to be resistant to both chemotherapy and radiotherapy [ 8 ]. There has recently been an emergence of case reports depicting the phenomenon of RCC spreading to the thyroid gland [ [1] , [2] , [3] , [4] , [5] , [6] , [7] , [8] ]. A common theme amongst these cases is a long lag phase between the treatment of RCC and the development of thyroid metastases – with a mean interval time of 9 years [ 6 ].…”