<prompt> Swelling over distal end of femur with secondaries in lungs, diagnosis is:Osteogenic sarcomaGiant cell tumorOsteoclastomaEwings sarcoma  <response>: Ans. is a ie Osteogenic sarcoma Osteosarcoma are aggressive lesion and metastasize widely through the blood stream; usually first to the lungs.Ewings sarcoma also metastasizes, to lung bones. Bone to bone metastasis are more commonOsteoclastoma rarely metastasizes.Thus this lesion could be either osteosarcoma or Ewings sarcoma but osteosarcoma would produce swelling at distal end of femur bc it arises from metaphysis and Ewing would not be placed distally bc it arises from the diaphysis. 