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Figure 7. (a) Aggressive bone lysis in the proximal humeral metadiaphysis. A permeative pattern of destruction is seen, with multiple tiny lucencies projected over the medulla, implying cortical involvement. There is an interrupted periosteal response (curved arrow) and an extraosseous mass is evident (arrows). (b) Sagittal short tau inversion recovery (STIR) and (c) T1 MR images show more extensive medullary involvement than suggested by the radiograph. Tumour crosses the growth plate into the epphysis, and extends through the cortex (arrows). The lesion is surrounded by oedema, which is hyperintense to the intermediate signal tumour on the STIR image. (d) Axial T2 weighted MR image showing circumferential extraosseous tumour and surrounding oedema. Diagnosis: Ewing's sarcoma.
