Abstract
INTRODUCTION: Metaplastic breast carcinoma (MBC) is a rare form of breast cancer, comprising less than 1 % of all breast malignancies. Osseous differentiation is an extremely rare subtype of MBC, accounting for only 0.003-0.12 % of all breast cancer cases. CASE PRESENTATION: We report a case of advanced-stage metaplastic breast carcinoma with osseous differentiation. The patient received neoadjuvant chemotherapy, but then the tumor progressed to metastasis. Despite palliative surgery, and chemotherapy, the disease did not respond; the patient died shortly later. CLINICAL DISCUSSION: Metaplastic breast carcinoma with osseous differentiation often rapidly progressive, resistant to chemotherapy, and associated with a poor prognosis. Some studies in the literature suggest that MBC tends to spread through the blood rather than lymphatic spread and therefore leads to lung and bone metastases. CONCLUSION: These findings suggest that the role of neoadjuvant chemotherapy in this histopathological group is limited and its use should be carefully considered.