Giant calvarial metastasis from secondary Ewing sarcoma with chronic subdural hygroma in a childhood hematological cancer survivor - An unusual case report.

We report an unusual case of a 9-year-old boy with Hodgkin lymphoma post chemoradiotherapy, who later developed Ewing sarcoma involving the eighth rib, which had metastasised to the cranial vault with meningeal and subdural involvement. Presenting with seizures, headache and hemiparesis, he underwent craniotomy and gross total tumour resection, with histopathology confirming metastatic Ewing sarcoma. Despite initial improvement, the patient presented with further cranial metastasis on follow-up. This case contributes to the limited literature on Ewing sarcoma metastasis to the CNS in patients with prior hematologic malignancies, questioning potential links between therapeutic chemoradiotherapy exposures and secondary cancer development. This case emphasises the unusual metachronous presentation of Hodgkin lymphoma and Ewing sarcoma and the high risk of recurrence and CNS involvement in cranial Ewing sarcoma, highlighting challenges in management and prognosis.