[A Case of Breast Carcinoma Associated with Osteoclast-Like Giant Cells].

Mammary carcinoma with osteoclast-like giant cells is uncommon, and its onset mechanism and malignancy are unknown. We report a case of mammary carcinoma with osteoclast-like giant cells. A 41-year-old woman noticed a lump in her left breast. Ultrasound sonography findings suggested breast cancer. A core needle biopsy revealed invasive ductal carcinoma of the breast. Modified radicalmastectomy and sentinell ymph node biopsy were performed. Histopathologicalexamination revealed papillotubular carcinoma with osteoclast-like giant cells. Cells were positive for estrogen receptor and progesterone, and negative for HER2. MIB-1 index was under 5%. The giant cells were generally associated with an inflammatory, fibroblastic, hyper-vascular stroma. The carcinomatous part of the lesion was most frequently a well-to moderately differentiated invasive ductalcarcinoma. Immunohistochemicaland ultrastructuralstudies suggested that the osteoclast-like giant cells were of stromalhistiocytic origin. To understand biochemicalfindings of this carcinoma, more case studies are required to be reported.