Figure 2: 34 year old patient with a large destructive soft tissue mass of the right hemipelvis. Coronal T1-weighted (a) and axial T2-weighted (b) MRI images demonstrate calcific lobules and punctuated foci with low signal intensity representing calcifications, which are typical for chondroid matrix. Histological analysis revealed a dedifferentiated chondrosarcoma. After resection of the affected bone a custom-made pelvic metal prosthesis was fitted into the defect. Radiograph one year postoperatively (c) shows a stable prosthesis, the functional and clinical outcome of the patient was good.