“…A pelvic sarcoma is a particularly difficult surgical problem when the posterior ilium is involved [4,16,17,20]. Unlike sarcomas of the extremities that rarely cross nearby joints, posterior iliac tumors frequently infiltrate the sacroiliac joint probably owing to relative joint immobility, increased local vascularity, and the large size of most pelvic lesions [1,4,9,11,19,20]. Despite difficulties caused by peritumoral edema, marrow signal changes, and unevenness of sacroiliac joint plane, interpretation of MR images in iliosacral lesions has a sensitivity of 100% and specificity of 92% [20].…”