Successful regression of metaplastic triple-negative breast cancer with neoadjuvant chemotherapy and surgical intervention: A case report

Rationale:Metaplastic breast carcinoma (MBC) is a rare, aggressive subtype of triple-negative breast cancer, accounting for 0.2% to 5% of all breast cancers. It is associated with poor prognosis, twice the recurrence rate, and resistance to chemotherapy. This case report presents the treatment and outcome of a 39-year-old female with locally advanced stage III MBC.Patient concerns:The patient presented with a right breast mass, which had increased in size despite prior incomplete excision. She also had a contralateral breast mass, which was later confirmed as a benign neoplasm.Diagnoses:The patient was diagnosed with metaplastic carcinoma of the right breast, classified as triple-negative breast cancer due to the absence of estrogen, progesterone, and human epidermal growth factor receptor 2 receptors. A biopsy revealed mesenchymal differentiation with a Nottingham grade 3 tumor measuring 35 mm, with high mitotic index and positive surgical margins.Interventions:The patient underwent neoadjuvant chemotherapy with taxane/carboplatin, followed by modified radical mastectomy and axillary lymph node dissection on the right, and subcutaneous mastectomy with sentinel lymph node dissection on the left. Post-surgery, she received adjuvant chemotherapy and radiotherapy.Outcomes:Following neoadjuvant chemotherapy, significant morpho-metabolic tumor regression was observed. Postoperative imaging demonstrated near-complete resolution of the tumor and metastases. The patient's quality of life improved significantly, despite the emotional and physical challenges of the treatment.Lessons:This case highlights the potential efficacy of combining neoadjuvant chemotherapy, surgery, and adjuvant therapy in the management of MBC, emphasizing the need for careful monitoring of clinical, histological, and imaging data to guide treatment decisions for this rare cancer subtype.