Metaplastic breast cancer (MBC) is characterized by the histological presence of a mixture of epithelial and mesenchymal-like elements. However, MBC responds poorly to chemotherapy. Due to its rarity, there is no well-defined treatment for MBC. Herein, we report the case of a 56-year-old woman who underwent a mastectomy and was diagnosed with MBC with osseous differentiation classified as pT4N0M1. After the operation, she was treated with adriamycin and cisplatin, which are standard osteosarcoma treatments, resulting in a partial response. However, to determine the proper chemotherapy treatment, knowledge of the metaplastic elements of the tumor is required.
Keywords: adriamycin and cisplatin; chemotherapy; metaplastic breast cancer; osseous/cartilaginous differentiation.