Abstract

Biphasic metaplastic sarcomatoid carcinoma (MSC) of the breast is rare and aggressive. Patients with metaplastic breast carcinomas tend to have poor outcomes with a high risk of recurrence following primary surgery. Most reports have shown that systemic therapy appears to be less effective. We report a case of a 42-year-old female who presented with a large (14 cm) cauliflower breast mass. Biopsy revealed a poorly differentiated sarcoma. Initially, neo-adjuvant concurrent chemoradiotherapy with a sarcoma regimen was prescribed, and the tumor regressed to a large ulcer. Subsequent biopsy showed invasive ductal carcinoma (estrogen receptor, progesterone receptor stained weakly, 5%, Her2:2+) and disappearance of the sarcomatous component. Second-line neoadjuvant therapy was designed according to the histologic features of infiltrating ductal carcinoma, which led to nearly a complete response. A modified radical mastectomy of the right breast and axillary dissection was performed followed by monoclonal antibody (trastuzumab) therapy for 6 months due to the surgical specimen showing Her2:3+. The treatment course went smoothly with a good response. The patient had no evidence of disease at 18 months.