Abstract

An 83-year-old woman with long-standing chronic ischemic cardiac and obstructive pulmonary disease, presented with a painless tumor in her right breast. Microscopically the tumor consisted of micropapillary formations and loosely cohesive nests and strands of large, highly pleomorphic cells. Micropapillary formations were surrounded by peritumoral retraction clefting, and the papillae lacked a true fibrovascular core. Multinucleated giant and bizarre tumor cells were also present and numerous. Within the tumor a high-grade intraductal component with the same cell morphology and necrosis and mucin production was found. Micropapillary pattern occupied approximately 60% of the tumor mass, loosely cohesive nests and strands approximately 20% and an intraductal component was noted in approximately 20% of the tumor mass. On immunohistochemistry the tumor cells were positive for pan-cytokeratin, epithelial membrane antigen (EMA), S100 protein and E-cadherin while estrogen and progesterone receptors, HER2-neu and Bcl2 were negative. EMA staining was diffuse and observed in the outer and inner margins of neoplastic nests. The diagnosis of pleomorphic breast carcinoma with predominant micropapillary features was established. In summary, micropapillary carcinoma can be distinguished from other types of breast carcinoma with micropapillary growth pattern on the basis of reverse cell polarity, which is easily confirmed on immunohistochemistry.