Abstract
INTRODUCTION: To the best of our knowledge, this is the first case report of a multifocal (trifocal) invasive carcinoma of the breast containing osteoclast-like giant cells. CASE PRESENTATION: A 64-year-old Caucasian woman presented for routine mammography screening with three radiodense lesions in the lower inner quadrant of the right breast, a primary breast cancer. Microscopic examination showed three foci of invasive ductal carcinoma with multinucleated osteoclast-like giant cells. Osteoclast-like giant cells in breast cancer are a rare phenomenon. They are described in less than two percent of all breast cancers and occur in association with invasive ductal cancer and invasive lobular cancer. In addition, osteoclast-like giant cells have been described in several sarcomas and metaplastic carcinomas of the breast. CONCLUSION: To the best of our knowledge, this is the first report of a multifocal infiltrating ductal carcinoma of the breast containing osteoclast-like giant cells. This could be an indication for a possible early event in carcinogenesis associated with a biological event or secretion that indicates the differentiation and/or migration of stromal cells or macrophages.