Primary osteosarcoma of the breast

Primary osteosarcoma of the breast is a rare malignant tumour. We report such a case in a 77-year-old lady who presented with a hard lump which was clinically and mammographically indistinguishable from a calcified fibroadenoma. Wide local excision of the lesion was carried out. Detailed histological and immunohistochemical features of the tumour are described. Because there was no evidence of metastasis and adequate local excision, no further treatment was considered necessary and she remains disease free at 39 months.