Primary osteogenic sarcoma of the breast

A rapidly growing tumor in the left breast of a 38-year-old woman was mammographically suggested to be a fibroadenoma because of its sharply circumscribed and quite homogeneous shadow, with coarse calcifications. Fine needle aspiration biopsy showed an unusual cytologic picture, with polymorphous and multinucleated giant tumor cells and scattered plaques of osteoid. After excision followed by mastectomy, the tumor was histologically diagnosed as an osteogenic sarcoma. Radiologically, there was no evidence of another tumor localization. The cytologic findings of this rare tumor, never previously reported, are presented.