Brain metastasis in a patient with a sarcomatoid variant RCC with well-controlled extracerebral metastases by temsirolimus.

BACKGROUND The sarcomatoid variant of metastatic renal cell carcinoma (RCC) has often an aggressive course and a poor prognosis, particularly when accompanied with brain metastasis. CASE REPORT We describe the case of a patient with sarcomatoid variant RCC in whom brain metastasis was observed as a new lesion during treatment with temsirolimus, despite other extracerebral metastatic lesions being well-controlled and progression-free. RESULTS This discrepancy between the effectiveness of temsirolimus for extracerebral metastases and the simultaneous progression of brain metastases of RCC raises a concern that while vascular endothelial growth factor (VEGF)-targeted therapy may have clinical efficacy, it may also carry a risk for new brain metastases due to weakening of the structure of the blood brain barrier. CONCLUSION This case indicates that computed tomography monitoring of the brain should be regularly performed during VEGF-targeted therapy in patients with sarcomatoid variant RCC, even if brain metastases are absent and extracerebral metastatic lesions are well controlled.