What test should be performed next and why?
The MRI locally staged the tumour and demonstrated widespread pelvic involvement. A bone scan allows assessment of the entire skeleton for distant metastatic bony disease and, if a complete three-phase study is performed, blood flow to the region. A CT of the chest and abdomen would also be useful to assess for solid organ metastatic disease.
Distribution of Ewing sarcoma. Most frequent locations are the large long bones and the pelvis.
Layout and distribution: Frank Gaillard 2009, Line drawing of skeleton: Patrick Lynch 2006, Creative Common NC-SA-BY