Clinical Presentation

A 9-year-old with progressive hip pain.

Further Work-up

(A) Anteroposterior radiograph of the pelvis: there is an aggressive lesion in the left superior pubic ramus with a periosteal reaction (arrow) and an associated soft-tissue mass. (B) Axial computed tomography (CT) image: there is destruction of the left acetabulum (arrow), with an associated large soft-tissue mass.

Differential Diagnosis

• Ewing sarcoma: These findings are typical of Ewing sarcoma.

• Osteosarcoma (OS): Typically presents as a large, mixed sclerotic/lytic lesion with a cloudlike matrix. It is less likely to occur in flat bones.

• Chondrosarcoma: Most commonly occurs in patients older than 40 years and rarely in children.

Essential Facts