A vertebral mass in an otherwise well child which has no matrix mineralization / ossification has a relatively limited differential including:

• benign
  • eosinophilic granuloma
  • aneurysmal bone cyst: fluid fluid levels would be typical
  • giant cell tumor
• malignant
  • Ewing sarcoma
  • lymphoma 

Given the clearly aggressive interface with bone, which is destroyed, a malignancy was unfortunately the most likely diagnosis in this case, and Ewing's sarcoma the most likely entity.