Fig. 1

Imaging results of patient at diagnosis (a/b) and last follow-up 26 months later (c/d). a Axial MRIs of the pelvis showing chrondroblastic osteosarcoma of the left Os ileum with infiltration of gluteal muscles, left iliac and obturatorius internus muscle, periosteous soft tissue, Os sacrum and Os pubis with strong contrast enrichment. T₁-weighted transversal MRI with i.v.-contrast-medium (gadoteriol, Prohance®, Bracco) and fat saturation (above) and T₂-weighted transversal MRI (bottom). b Aside from intensive bone turn over at the left hemipelvis, no other suspicious bone lesions are observed in initial bone scan. c Axial MRIs of the pelvis showing residual proportions of chrondroblastic osteosarcoma of the left Os ileum with decreasing contrast enrichment and signs of sclerosis and ossification of small soft tissue component. T₁-weighted MRI with contrast agent and fat saturation (above) and T₂-weighted MRI (bottom). d Bone scan demonstrating a normalisation of bone turn over at the left hemipelvis. MRI could rule out an initially suspected left parietal metastasis. Aside from an accentuation of the right sacroiliac joint due to incorrect weight bearing, no other suspicious bone lesions were observed