[Malignant giant cell tumor of the femur with sarcomatous changes (author's transl)].

This is the report of a case with recurring giant cell tumor of the femur, which showed roentgenological evidence of pulmonary metastases. Only at the third biopsy sarcomatous changes as morphological signs of malignancy were found. Contrary to some elsewhere published giant cell tumors with sarcomatous components, there was no preceding irradiation in our case.