Metaplastic carcinoma of the breast: A case series and review of the literature

Abstract

Purpose: Metaplastic breast carcinoma (MBC) is a rare aggressive type of breast cancer, which accounts for less than 1% of breast tumors. Since its recognition as a distinct pathological entity in 2000, number of MBC patients has been increasing over years. We aimed to report a series of 7 cases of MBC treated in our clinics. Materials and methods: Between 2006 and 2015, 7 cases with diagnosis of MBC were retrospectively reviewed. Patients' characteristics, clinicopathological features and types of surgery were evaluated. Results: All patients were female with a median age of 51(40–65) years. Median tumor size was 40 mm (35–85 mm). Two patients had breast-conserving surgery and 4 patients had mastectomy. One patient received chemotherapy due to extensive metastatic disease at the time of presentation. Only one patient had one positive sentinel lymph node with no other involvement in the non-sentinel nodes. Two patients had spindle cell carcinoma, 2 patients had pure epithelial type, and 3 patients had mixed epithelial and mesenchymal type MBC. Most common component of MBC was squamous cell metaplasia that was found in 4 out of 7 patients. Six patients had triple negative tumors except the patient with disseminated disease. This patient had estrogen receptor positive, progesterone receptor negative tumor with human epithelial receptor-2 (HER2) over-expression. Median Ki67 score measured in 5 patients was 57% (40–95%). Conclusion: Our small series is consistent with the literature. MBC rarely metastasize to axillary lymph nodes despite large size and are usually triple negative with high Ki-67 scores indicating aggressiveness and lack of response to hormonal therapy. Larger series of patients are needed to find and test new biomarkers to develop potential targeted therapy for subgroups of the disease.

Keywords

• Metaplastic breast carcinoma
• Basal like phenotype
• Triple negative breast cancer