Heterologous Metaplastic Carcinoma

Comments:
Heterologous metaplastic carcinoma of the breast (same case as the previous two images). Highly atypical tumor cells are seen lining malignant osteoid matrix which is largely unmineralized (except for a small area near the top center and left). The intervening space between the osteoid trabeculae is filled with high-grade spindle cells. This tumor was composed entirely of spindle cells and heterologous elements.