Differentiating Osteosarcoma from Ewing Sarcoma

Clinical and Demographic Features

Osteosarcoma shows a bimodal age distribution with the first peak in teenagers/young adults and a second peak in the seventh and eighth decades, according to the British Journal of Cancer 1, 3
Ewing sarcoma occurs predominantly in childhood and adolescence with a median age of 14 years, and 90% of patients are under 20 years, as reported by the Annals of Oncology 1, 4, 5
Osteosarcoma is slightly more common in Black patients, while Ewing sarcoma is distinctly less common in people of Chinese or Black African origin, according to the British Journal of Cancer and Annals of Oncology 1, 3, 4

Complex genome rearrangements via chromoplexy and chromothripsis are characteristic of osteosarcoma, as reported by Clinical Cancer Research 2, 6
TP53 loss-of-function mutations and MYC amplification are also associated with osteosarcoma, according to Clinical Cancer Research 2, 6
FET::ETS gene fusions, most commonly EWSR1::FLI1, are present in >90% of Ewing sarcoma cases, as reported by Clinical Cancer Research and Annals of Oncology 2, 4, 5, 6
MIC2 gene expression distinguishes Ewing sarcoma immunohistochemically from other pediatric "blue tumors", according to Annals of Oncology 4, 5, 7

The American Society of Clinical Oncology recommends a diagnostic algorithm that includes clinical assessment, imaging, and molecular testing to differentiate osteosarcoma from Ewing sarcoma 1, 4
The algorithm suggests considering Ewing sarcoma in patients under 20 years with non-Black ethnicity, and osteosarcoma in patients with bimodal age distribution, as reported by the British Journal of Cancer and Annals of Oncology 1, 3, 4

The National Comprehensive Cancer Network recommends referring patients to specialized bone sarcoma centers before biopsy to avoid tissue contamination that compromises subsequent management 4, 5, 7
Complete radiological assessment of the entire affected bone must be performed before any biopsy, as reported by Annals of Oncology and Praxis Medical Insights 4, 5, 7