[A Case of Metaplastic Squamous Cell Carcinoma of the Breast Diagnosed after Neoadjuvant Chemotherapy].

Metaplastic carcinoma is a rare type of breast carcinoma, which tends to be chemo-resistant. We report a case of metaplastic squamous cell carcinoma of the breast diagnosed after neoadjuvant chemotherapy(NAC). A 56-year-old woman was diagnosed as having right-sided breast cancer(invasive ductal carcinoma[IDC], triple negative), cT1cN1M0, stage II A. NAC with 5-fluorouracil, epirubicin, and cyclophosphamide(FEC)followed by docetaxel(DTX)was administered. Tumor progression occurred during both the FEC and DTX regimens. We discontinued NAC and performed breast conserving surgery with axillary lymph node dissection. Histological findings of the resected specimen showed mixed IDC and widely spread squamous metaplasia. Weekly paclitaxel and radiotherapy were administered and the patient is alive with no recurrence 3 years after surgery.