Figure 5. Radiograph of the left hip in a patient with histologically proved dedifferentiated chondrosarcoma demonstrates a nonspecific, malignant, purely osteolytic destructive lesion in the periacetabular region with extensive cortical destruction medially (arrows) and a soft-tissue mass along the pelvic side wall (arrowheads). The differential diagnosis would also include metastasis, lymphoma, and multiple myeloma.