Osteoclast-like Multinucleated Giant Cells

Abstract

Mammary carcinoma with osteoclast-like giant cells is a rare variant of infiltrating breast carcinoma, first described by Rosen in 1979. Clinically and on sonomammography, the well-circumscribed margin of these tumors may suggest a benign lesion such as fibroadenoma and lead to a false negative diagnosis, as in this case of a 46 year old female with right breast lump. Fine needle aspiration cytology showed cohesive clusters with minimal cellular atypia mimicking fibroadenoma. But, presence of osteoclast-like multinucleated giant cells in the background was puzzling. So, lumpectomy was performed. Histopathology showed well differentiated invasive duct carcinoma, confirmed as luminal A type on immunohistochemistry. Till date, over 200 cases have been reported worldwide but we describe probably the only case from India, with complete work-up. The purpose of sharing this experience is to avoid missing malignancy on cytology in lesions which radiographically mimic fibroadenoma, osteoclast-like giant cells being a clue. Immunohistochemistry plays a diagnostic and predictive role. This low grade, rare but unique breast carcinomas must be documented for optimal patient management.