Exuberant complex metaplastic carcinoma of the breast with SOX2 expression: Cove ring the full spectrum of ductal neoplasia of the breast

Abstract 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.