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Ewing Sarcoma — RACP Paediatrics MCQ

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ModerateHaematology & OncologyEwing SarcomaRACP Paediatrics

A 9-year-old boy presents with a 6-week history of a painful limp. X-ray of the left tibia shows a periosteal 'onion-skin' reaction with a permeative lytic lesion. Biopsy reveals small round blue cells. What is the most likely diagnosis?

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Correct answer: E — Ewing sarcoma

Ewing sarcoma typically presents in children and adolescents as a painful bone lesion with characteristic 'onion-skin' periosteal reaction (lamellated periosteum). Histology shows sheets of small round blue cells. The most common translocation is t(11;22) producing the EWS-FLI1 fusion gene. It most frequently affects the diaphysis of long bones and the pelvis.

Reference: ANZCHOG – 2024 – Treatment Guidelines: Ewing Sarcoma