Abstract:Metastasis to breast from extra-mammary sites is much less common as compared to primary ones and only few cases are reported in the literature. Furthermore, very little is known about prognosis and treatment of patients with solid neoplasms metastatic to the breast. If a breast lump is found, it is recommended to perform a bilateral mammogram specially when there is a rapidly enlargement. Here, we describe a case of a young woman with synchronic breast metastasis from asymptomatic, widely spread, renal cell carcinoma, Furhman grade 4. RCC is one of the most aggressive urologic tumors and rarely metastasizes to the breast. This phenomenon takes place in less than 3% of all metastatic renal cell carcinoma and the appearance as first sign of renal disease is exceptional. This case illustrates the importance of histopathological investigation in a breast mass and the potential for rare sites of metastasis in order to prevent unnecessary radical procedures. Also, this report contributes to importance of a proper diagnosis when rare sites of metastatic deposit, like breast, are detected, especially if there is no previous history of neoplasm.