Pleomorphic carcinoma of the breast with expression of macrophage markers: Report of two cases

Pleomorphic ductal carcinoma of the breast is a rare variant included in the morphological group of infiltrating ductal carcinoma. The pleomorphic carcinoma is composed predominantly of epithelial and multinucleated tumor giant cells. We report here two cases presenting a lesion composed microscopically of a proliferation of large pleomorphic cells with a predominance of multinucleated giant cells. These lesions were negative for estrogen receptor, progesterone receptor and Her2-neu (triple-negative phenotype). Basal markers (cytokeratin 5/6, cytokeratin 17 and epidermal growth factor receptor [EGFR]) were present, accompanied by the presence of histiocyte marker CD163 in most neoplastic giant cells. High-grade pleomorphic breast carcinomas with the triple-negative phenotype and expression of basal markers might be included in the basal subtype. This is the first report about the co-expression of macrophage marker CD163, with tumor (P53) or epithelial markers (CAM5.2), as indicated by double immunohistochemistry in pleomorphic ductal carcinoma of the breast.