Abstract
BACKGROUND: Metaplastic squamous cell carcinoma of the breast (MSCCB) is a rare and aggressive type of cancer. So far, no standard treatment regimen has been established due to the absence of clinical data. CASE DESCRIPTION: We report a case of a 48-year-old female admitted to our hospital as a result of a left breast mass with skin rupture. Core needle biopsy under ultrasonic guidance confirmed MSCCB. Immunohistochemistry revealed negative staining for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor type 2 (HER2/neu). After receiving 4 cycles of paclitaxel and carboplatin neoadjuvant chemotherapy, the patient was treated with modified radical mastectomy. Postoperative pathology revealed a Miller-Payne score of 4 and no metastasis in the axillary lymph nodes (0/13), indicating a good response to neoadjuvant chemotherapy. She recovered well post-surgery and was discharged to home after admission. No recurrence was identified during the 2 years post-surgery follow-up. CONCLUSIONS: MSCCB is a rare and aggressive type of cancer. However, the treatment of MSCCB has not been standardized due to its rarity. Given the observation that the majority of patients with MSCCB had ER, PR, HER2-negative neoplasms, we refer to the triple negative breast cancer (TNBC) treatment protocol. TP regimen was demonstrated to be an effective treatment for TNBC. The results of this case suggest that the TP regimen is effective in neoadjuvant chemotherapy of MSCCB.