[A Case of Breast Metastasis from Renal Cell Carcinoma]

The patient was a woman in her 90s. Right radical nephrectomy for right renal cell carcinoma had been performed 2 years and 6 months ago. Since then, there had been no recurrence. However, computed tomography during postoperative follow- up period showed a 3 cm mass in the right breast, and the patient was referred to our department. Breast ultrasonography indicated a well-circumscribed, oval, and almost smooth-surfaced tumor, 27 mm in size, located in the D region of the right breast. Results of a core needle biopsy showed metastatic renal cell carcinoma and clear cell carcinoma. Preoperative examination confirmed intramammary metastases of renal cell carcinoma. Given that the patient did not experience systemic metastases, partial mastectomy of the right breast was performed. Metastatic renal cell carcinoma is associated with poor prognosis. Generally, standard treatment in this disease is chemotherapy. However, surgical resection is selected with the aim of improving the prognosis and achieving radical cure of patients with this complication if these patients are in an oligometastatic state and complete resection of metastatic lesions is feasible, as in the present case. To achieve radical cure, the patient underwent partial mastectomy under local anesthesia, which is a relatively minimally invasive surgery.