Limb Salvage for Entire Tibial Ewing Sarcoma in a 4-year-Old Child Using Extracorporeal Irradiation and Free Flap Reconstruction: A Case Report and Surgical Technique.

INTRODUCTION: Ewing sarcoma of the tibial shaft in a very young child presents a significant limb-salvage challenge. Treatment requires effective local control while preserving limb function and accommodating future growth. Extracorporeal irradiation (ECI) with reimplantation is a biological reconstruction technique that utilizes the patient's own sterilized tumor-bearing bone. CASE REPORT: We present the case of a 4-year-old boy diagnosed with Ewing sarcoma involving the right tibial shaft. Staging investigations revealed localized disease with intense uptake on bone scan and a small, non-specific 2-mm pulmonary nodule. Following a multidisciplinary team decision, the patient was treated with neoadjuvant chemotherapy according to the Children's Oncology Group AEWS0031 protocol, followed by limb-salvage surgery. CONCLUSION: This case demonstrates that en bloc resection with ECI and reconstruction, combined with free vascularized flap coverage, is a viable and effective limb-salvage strategy for extensive Ewing sarcoma in very young children. This complex single-stage procedure provides durable biological reconstruction, addresses large soft-tissue defects, and offers the potential for long-term function and growth.