Pediatric Oncology Education Materials

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Ewing Sarcoma

Ewing sarcoma (ES):

Invades locally with bone destruction, involvement of adjacent soft tissues and intramedullary spread.
Ewing sarcoma of bone rarely spreads to adjacent lymph nodes. This is more commonly seen in a primary Ewing sarcoma arising in soft tissues (extra-osseous Ewing sarcoma).
Distant metastases - almost always hematogenous are common
- Most cases of ES have microscopic (clinically undetectable) spread at diagnosis.
- 25 - 30% of patients have clinically detectable metastatic disease at presentation.
If Ewing sarcoma occurs in a location (parameningeal or spinal) where there is invasion of the CSF pathways, leptomeningeal spread may occur.

Summary of ES routes of spread:

Local

Tumor infiltrates bone marrow and adjacent soft tissue
Plain films show a permeative destructive lesion of bone
The periosteum is typically displaced by the underlying tumor, resulting in the sign of Codman triangle
An associated soft tissue mass is typical
New bone formation is typical

Distant

If ES is treated without systemic chemotherapy, at least 90% of patients will develop distant metastases
Common sites for metastases: lungs, bone marrow, and bones
Metastases to lymph nodes are rare
Leptomeningeal spread is possible for tumors associated with CSF pathway invasion

Most common sites for ES metastatic disease: