[A case of breast adenocarcinoma changed to squamous cell carcinoma after neoadjuvant chemotherapy].

Squamous cell carcinoma(SCC)of the breast is a rare pathological-type cancer with an unclear origin. It has been suggested that breast SCC may originate from squamous metaplasia of the ductal epithelium. We report a case of SCC of the breast which histological carcinoma type changed after neoadjuvant chemotherapy. A 66-year-old woman visited our hospital for a tumor of the left breast. Mammography indicated breast cancer. On CT scan the tumor was 40mm in diameter, and was located in the upper lateral quadrant of the left breast. Because she requested breast-conserving surgery, core needle biopsy(CNB)was performed. The histological findings showed solid-tubular adenocarcinoma, PgR(-), ER(-), HER2(-), cT2cN1cM0, cStage II B. She received neoadjuvant chemotherapy consisting of 4 courses of CEF(cyclophosphamide, epirubicin, 5-fluorouracil)and 3 courses of paclitaxel. After chemotherapy, she was considered to have progressive disease, and a modified radical mastectomy was performed. The resected tumor was cystic and 60mm in diameter, containing muddy fluid. Histopathological examination showed pure squamous cell carcinoma, PgR(-), ER(-), HER2(-), pT3pN0pM0, pStage II B. The cancer metastasized with the light axillary lymph nodes at the 6th month after the operation, and she underwent chemo-radiation therapy. She died 6 years after the operation from brain metastasis.