A female patient in her 50s was diagnosed with triple negative breast cancer in the left breast with a buttock metastasis. After neoadjuvant chemotherapy, the patient underwent surgery on the left breast. As the histopathological findings indicated a residual tumor, she was further treated with capecitabine postoperatively. Twenty months postoperatively, a CT scan revealed a tumor on her left buttock. She was also diagnosed with a relapse of the breast cancer after a core needle biopsy. She was treated with atezolizumab and nab-paclitaxel as first-line therapy for the metastasis and with eriburlin as second- line therapy. As she became uncomfortable sitting owing to the regrowth of the buttock tumor, the left buttock tumor was resected. She has been treated with bevacizumab and paclitaxel for subsequent lung metastases.