Dedifferentiated chondrosarcoma with a rhabdomyosarcomatous component

A case of dedifferentiated chondrosarcoma arising in the femur with metastasis to the lung is described. On immunoperoxidase studies and electron microscopic examination, both the anaplastic soft tissue extension of this tumor in the hip and the metastatic lung nodule showed evidence of rhabdomyosarcomatous differentiation. This case represents the first documented case of a chondrosarcoma with differentiation into a rhabdomyosarcomatous component.