Purpose or Case Report: A 16 year old boy reporting several months of hip pain, weight-loss, and fatigue presented to our institution after a pelvis radiograph ordered by his family physician showed concerning findings. MR imaging of his pelvis demonstrated a large heterogeneously enhancing mass arising from the right iliac wing causing significant mass effect on the pelvic organs and soft tissues of the buttocks. A percutaneous biopsy confirmed the diagnosis of Ewing sarcoma.
A staging CT of the chest was performed, demonstrating multiple lung metastases. In addition to this finding, there was multifocal bilateral nodular tumor thrombus propagating along multiple subsegmental pulmonary arteries, with a pseudo tree-in-bud morphology. Given their course, these metastatic deposits appeared endovascular in origin.
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Conclusions: Ewing sarcoma is the second most common bone malignancy in children and adolescents with a predilection for primary sites in the axial skeleton, particularly the pelvis. The presence of metastatic disease at diagnosis – present in approximately one quarter of patients – is predictive of poor clinical outcomes. Metastastectomy and radiotherapy to pulmonary metastases are thought to improve survival in these patients.
While not a true sarcoma, this malignancy shares the metastatic pattern of sarcomas, which is hematogenous and usually to the lung, although its lymphatic spread has also been described. To our knowledge no report of pulmonary endovascular seeding and spread of Ewing sarcoma has ever been made.