Metaplastic breast cancer with heterologous mesenchymal differentiation (osseous and chondroid): A case report and review of the literature

This report describes a rare case of metaplastic breast carcinoma (MpBC) with heterologous mesenchymal differentiation (osseous and chondroid) in a 72-year-old woman. The patient presented with a lump in the right breast which initially posed diagnostic difficulties due to its unusual radiological features. Imaging studies, including mammography, ultrasound, and MRI, revealed a tumor with mesenchymal differentiation, which was confirmed by ultrasound-guided core-needle biopsy. We discuss the clinical course, the typical resistance to chemotherapy seen in MpBC, and the surgical treatment undertaken, comparing these findings with data from the current literature. This case highlights the need for a comprehensive multimodal evaluation for an accurate diagnosis of MpBC.