[An extraosseous osteoblastic osteosarcoma in the breast mimicking a pulmonary coin lesion on the chest radiograph (author's transl)].

Case report of an osteoblastic osteosarcoma in the breast, which in addition to its unusual presentation caused some differential diagnostic problems initially because it mimicked a pulmonary coin lesion. One year later a metastasis was noted which had the same x-ray features as the primary tumor.