A 14-year-old girl from rural India presents with a 6-week history of pain and swelling in the left tibia. She reports fever on and off and has lost 2 kg of weight. On examination, there is localized warmth, tenderness, and a firm mass over the anterior tibia. Laboratory tests show hemoglobin 10.2 g/dL, WBC 14,500/μL, ESR 95 mm/hr, and CRP 18 mg/dL. Plain radiographs show a mixed lytic and sclerotic lesion with a wide zone of transition and cortical destruction. CT chest is normal. A biopsy shows small round blue cells with high mitotic activity and EWSR1-FLI1 fusion gene detected on molecular testing. What is the most appropriate next step in management?

Explanation

## Management of Ewing Sarcoma: Multimodal Therapy ### Diagnosis Confirmation **Key Point:** The EWSR1-FLI1 fusion gene is pathognomonic for Ewing sarcoma and confirms the diagnosis. Histology showing small round blue cells with high mitotic activity is also classic. ### Treatment Algorithm ```mermaid flowchart TD A[Ewing Sarcoma Diagnosed]:::outcome --> B[Staging: CT chest, bone scan/PET]:::action B --> C{Metastases?}:::decision C -->|No| D[Neoadjuvant Chemotherapy]:::action C -->|Yes| E[Neoadjuvant Chemotherapy + Intensified Regimen]:::action D --> F[Reassess with Imaging]:::action E --> F F --> G{Good response?}:::decision G -->|Yes| H[Surgery ± Radiation]:::action G -->|No| I[Radiation Therapy]:::action H --> J[Adjuvant Chemotherapy]:::action I --> J J --> K[Long-term Surveillance]:::outcome ``` ### Why Neoadjuvant Chemotherapy? **High-Yield:** Ewing sarcoma is exquisitely chemosensitive. Neoadjuvant chemotherapy: 1. Shrinks the primary tumor, facilitating surgical resection 2. Treats micrometastases early 3. Allows assessment of histological response (good prognostic indicator) 4. Improves overall survival from ~10% (surgery alone) to 70–80% (multimodal therapy) **Clinical Pearl:** The standard regimen is typically **VIDE** (vincristine, ifosfamide, doxorubicin, etoposide) or **EVAIA** (etoposide, vincristine, adriamycin, ifosfamide, actinomycin D) followed by surgery and/or radiation, then continuation of chemotherapy. ### Why NOT the Other Options? | Option | Why Incorrect | | --- | --- | | **Wide local excision first** | Without neoadjuvant therapy, micrometastases are not treated; survival is poor. Neoadjuvant shrinks the tumor and improves resectability. | | **Amputation** | Modern limb-salvage surgery combined with chemotherapy achieves >70% 5-year survival. Amputation is reserved for cases with vascular/nerve involvement or poor chemotherapy response. | | **Palliative care only** | Ewing sarcoma is a curable malignancy in adolescents with multimodal therapy. Palliative care is inappropriate as first-line management. | ### Prognostic Factors **Key Point:** Good prognostic factors in this case: - Age 14 (younger is better) - Tibia (lower limb; better than pelvis/spine) - No evidence of metastases on staging - Likely good chemotherapy response (to be assessed after neoadjuvant phase) **Mnemonic: VIDE** — **V**incristine, **I**fosfamide, **D**oxorubicin, **E**toposide (common neoadjuvant regimen for Ewing sarcoma). [cite:Robbins 10e Ch 26]