Abstract

Malignant tumors of the breast which contain stromal osteoclast-like, multinucleated giant cells are a rare entity of yet unknown clinical significance. These benign multinucleated giant cells are known to occur mostly in areas of prominent angiogenesis and in close association with tumor cells. Supplementary immunohistochemical and electronmicroscopic examinations indicate that the multinucleated giant cells are of histiocytic origin. We report on a case of infiltrating ductal carcinoma with stromal osteoclast-like multinucleated giant cells occurring in the right breast of a 37 year-old woman. Grossly, the tumor was characterized by a well-circumscribed dark brown, solid firm mass. Microscopically, multinucleated giant cells were found in the stroma intermingled with malignant tumor cells. The stroma showed only a small amount of mononuclear cell infiltration and a moderate degree of vascular proliferation. Immunohistochemical stains revealed the tumor cells to be positive for carcinoembryonic antigen, epithelial membrane antigen and cytokeratin while the multinucleated giant cells were positive for vimentin, CD68 and negative for all other stains tested. Ultrastructurally the multinucleated giant cells differed from tumor cells by having abundant cytoplasmic organelles such as rough endoplasmic reticulum, lysosomes, ribosomes, and vesicles but lacking desmosomes or other types of intercellular junctions. Other characteristic features of multinucleated giant cells included, indented nuclei and prominent cytoplasmic process.

• Keywords: Osteoclast-like multinucleated giant cell;Breast carcinoma;