Abstract
The patient is a 75-year-old man who underwent nephrectomy for renal cell carcinoma (clear cell carcinoma) in 2008. Follow-up enhanced computed tomography in 2011 showed a 7mm diameter tumor in the left breast, and the tumor subsequently increased to 13mm in diameter after six months. We suspected that the breast tumor was a primary or metastatic carcinoma from renal cancer. Ultrasonography demonstrated the features of the tumor, which were a well-circumscribed hypoechoic mass with abundant vascularity. The findings of core needle biopsy suggested a metastatic breast tumor from clear cell carcinoma. Male breast cancer is rare, accounting for less than 1% of all breast cancer cases. Furthermore, metastatic male breast cancer is an extremely unusual disease. It is known that the primary tumors of metastatic breast cancer are contralateral breast cancer, gastric cancer, leukemia, and malignant lymphoma. However, renal cell carcinoma has been rarely reported. To our knowledge, this is a first report in Japan related to metastatic male breast cancer from renal cell carcinoma.
