Breast metastasis from primary renal cell carcinoma, ten years after nephrectomy

Abstract Background Metastasis to the breast from non-breast tumors is uncommon, and breast metastasis from renal cell carcinoma (RCC) is extremely rare. Despite the high incidence of primary breast cancer, it is important to consider metastasis from other cancers in patients with a history of malignancies. Case presentation A 60-year-old female with a history of right nephrectomy for RCC 10 years prior, who had missed follow-up for 7 years, presented with hepatic metastases that had been under treatment for the past 2 years. During routine follow-up, a small lesion in her right breast was incidentally found on chest-computed tomography. She was referred for further imaging, and mammography and ultrasound revealed a BI-RADS 3 lesion. Six months later, the lesion had grown rapidly, and a follow-up CT showed a tripling in size along with an increase in the size and number of hepatic metastases. A biopsy of the breast lesion confirmed it as metastatic RCC. Conclusions This case is unusual due to the rare site of metastatic spread. Physicians should be aware of considering metastasis when new breast lesions appear in patients with a history of RCC. A biopsy should be considered essential in such cases to ensure accurate diagnosis.