Breast cancer with osteoclast-like giant cells interpreted as a cyst: A case report

Objective: We describe a patient with breast cancer with osteoclast-like giant cells. Methods: The tumor was initially interpreted as a cyst at clinical examination, mammography, and ultrasonography. Breast cancers with osteoclast-like giant cells are rare. Because they are often circumscribed, they can be misinterpreted as benign tumors or cysts at mammography. On gross examination such tumors are often well defined and show a characteristic reddish brown cut surface. Results: Histologically the highly vascular tumor stroma is hemorrhagic and contains numerous osteoclast-like giant cells, probably of histocytic origin. Conclusion: The osteoclast-like tumor component is not of independent prognostic significance. Surgical and adjuvant treatment are the same as for other breast cancers.