[A case of myocardiac metastasis of clear cell renal carcinoma successfully treated with sunitinib].

A 65-year-old male was referred to our clinic from orthopedics because his right gastrocnemius muscle tumor was diagnosed as a metastatic renal cell carcinoma (RCC) with clear cell/spindle cell morphology. He had right nephrectomy for RCC 18 years previously. At 17 months following the first visit to our clinic, brain, lung and right gluteus medius muscle metastases were identified on positron emission tomography computed tomography (PET-CT). The echocardiogram for the evaluation of his heart function incidentally revealed a 3 cm nodular lesion in the right ventricular wall suggesting myocardiac metastasis. He started to take sunitinib at a standard dose of 50 mg/day. A subsequent echocardiogram during the 2nd cycle of sunitinib showed complete disappearance of the myocardiac metastasis. After the 2nd cycle, PET-CT revealed a partial response (PR) for the other metastases. He received 8 cycles of sunitinib. The best response was PR, and progression-free survival was 6 months. After that, he took everolimus for 7 months. Although the myocardiac metastasis continued to show a complete response during the treatment course, he died of progressive lung metastases at 21 months following the administration of sunitinib. Diagnosis of myocardiac metastasis of RCC during the treatment course as well as its successful treatment with molecular targeting agents has rarely been reported.