Imaging characteristics of metaplastic breast cancer with osteoblastic differentiation.

An 82-year-old female presented to her breast surgeon with a hard, painful mass in the left breast. Mammography demonstrated a new hyperdense mass with pleomorphic calcifications of trabeculated appearance. Ultrasound-guided biopsy demonstrated a hypoechoic mass with significantly increased vascularity and tissue stiffness as well as additional irregular, hypoechoic masses in the same area. Together these findings suggested multifocal malignancy. The pathology report from the biopsy demonstrated fragments of solid sheets of epithelioid and focally spindled cells with multinucleated osteoclast giant cells. This was found to be most consistent with metaplastic carcinoma showing osteoblastic differentiation. The patient received a left-sided mastectomy. During follow-up with the patient, adjuvant chemotherapy was not advised given the relatively unknown survival advantage in this elderly patient. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.