Fig. 1

Coronal X-ray (A) and gadolinium-enhanced T1-weighted MRI (B) images demonstrating a unifocal lesion in the left proximal humeral diaphysis at time of diagnosis. After seventeen months and two surgical interventions, axial gadolinium-enhanced T1-weighted MRI demonstrated progressive disease with significant soft tissue extension (C). Radiation treatment plan of the humerus. The planning target volume (PTV) is indicated by the red line, the clinical target volume (CTV) by the blue line, and gross tumor volume (GTV) by the yellow line (D). Three months following RT, T2-weighted MRI demonstrates a full radiological response (E). Successive PET-CT images show strong FDG uptake in the bone and surrounding soft-tissues, with a remarkable decrease in both tumoral mass and FDG uptake after RT, compatible with a complete radiological response (F). Abscess-like soft tissue extension through the skin prior to RT (G). Clinical response at 9 months post RT (20 Gy in 10 fractions) showing marked improvement of skin and subcutis inflammation (H)