We report a unusual case of a 45-year-old woman with a massive metaplastic carcinoma of the breast with a complex admixture of components including giant pleomorphic cells, sarcomatoid areas, cysts with undifferentiated stratified epithelium, squamous carcinoma foci, high grade comedo-type ductal carcinoma in situ, high grade invasive carcinoma not otherwise specified (NOS) and foci with osseous differentiation. An extensive immunohistochemical panel showed expression of both epithelial and mesenchymal markers. The self-renewal marker SOX2 was expressed in different cell types, which was interpreted as a sign of the pluripotency what can in turn explain the diversity of histologic lineages present in this tumour.