Breast metastasis in osteosarcoma.

A young girl with a history of chondroblastic osteosarcoma of the tibia developed a pulmonary metastasis which was treated by metastasectomy, chemotherapy and lung irradiation. There years later, at the age of 15, she developed a breast mass which was excised and which proved to be a poorly differentiated sarcoma. This was almost certainly a metastasis rather than a radiation-induced second primary tumour, in view of the short interval since radiotherapy. The ultrasonographic features of this lesion are presented here and the differential diagnosis is discussed in this context.