Neoadjuvant chemotherapy-enabled tumor conversion and surgical resection in pediatric primary pulmonary Ewing sarcoma: a case report

Figures

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  Figure 1. Serial chest radiographs and CT scans. Composite imaging illustrates the tumor’s evolution. (A) Pre-chemotherapy posteroanterior chest radiograph showing a large opacity in the right lower lobe with bronchial obstruction, initially misdiagnosed as pneumonia. (B) Pre-chemotherapy lateral chest radiograph confirming the mass located posterior to the cardiac silhouette. (C) Post-chemotherapy (preoperative) chest radiograph demonstrating partial resolution of the opacity with improved aeration, indicating a partial therapeutic response and conversion to a resectable state. (D) Pre-chemotherapy axial CT (lung window) revealing a heterogeneous right lower lobe mass (33 × 32 × 27 mm) with calcification and bronchial compression. (E) Post-chemotherapy axial CT showing tumor shrinkage and relief of bronchial obstruction, highlighting the conversion effect. (F) One-month postoperative axial CT demonstrating a clear lung field without residual tumor, confirming successful surgical resection. These serial images underscore the role of diagnostic assessment, treatment response, and multidisciplinary management.

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  Figure 2. Histopathological findings of pre-biopsy and resected specimens. (A–C) Initial endobronchial biopsy showing small round blue cell morphology with scant cytoplasm, arranged in sheets, consistent with a malignant small round cell tumor (H&E staining, magnification ×200). (D–F) Postoperative resected specimen demonstrating features of extraskeletal EWS/PNET. Tumor cells are densely packed with hyperchromatic nuclei and inconspicuous nucleoli, displaying a diffuse sheet-like growth pattern [H&E staining, magnification ×100 for D, ×200 for (E, F)].

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  Figure 3. Preoperative PET-CT findings. Preoperative PET-CT demonstrating a heterogeneous mass in the dorsal segment of the right lower lobe (33 × 32 × 27 mm) with coarse calcifications and uneven FDG uptake (SUVmax: 4.9). The lesion caused partial bronchial narrowing, but no abnormal FDG uptake was detected in the mediastinal lymph nodes or distant organs, suggesting localized disease.

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  Figure 4. Resected right middle and lower lobes with tumor mass.