386 Metaplastic carcinoma of the breast

Introduction/Background Metaplastic carcinoma of the breast is a rare entity containing a mixture of malignant epithelial and mesenchymal elements. The World Health Organization only recognized it as a distinct pathological entity in 2000. This study aims to characterize this rare disease better. Methodology We reviewed retrospectively 15 cases of metaplastic carcinoma of the breast treated in our institute between 2008 and 2022. We analyzed clinical, histological, therapeutic, and evolutive data. Results All patients were females ranging from 28 to 76 years old. Tumor size ranged from 20 to 155 mm (median, 72 mm). The Treatment consisted of radical mastectomy in 14 cases, often combined with postoperative radiation and chemotherapy. There were 8 cases of carcinosarcoma, 4 cases of spindle cell carcinoma, and 3 cases of squamous cell carcinoma. Follow-up data were available on 12 patients. The median follow-up was 46.5 months. Definitive nodal metastases were identified in 7 cases. One patient developed a local recurrence. Extranodal metastases occurred in 3 patients. Three patients died at a median interval of 22 months (range 13–33). Eight patients were alive with no evidence of recurrent or metastatic disease, and one patient was alive with metastatic disease. Conclusion Based on this series, metaplastic breast carcinoma is characterized by a large tumor size at presentation, a low frequency of nodal metastases, and a high proportion of triple negativity. Our series is consistent with the literature. Disclosures Concerning these cases, I declare that there are no conflicts of interest.