Primary Ewing Sarcoma of the urinary bladder in an adolescent: a case report of successful organ preservation with multimodal therapy

Introduction and importance: Primary bladder sarcomas, particularly Ewing Sarcoma/primitive neuroectodermal tumor (ES/PNET), are exceptionally rare in the pediatric and adolescent population, presenting diagnostic and therapeutic challenges. Case presentation: A 15-year-old Syrian girl from a rural area, presented with lower abdominal pain and gross hematuria. Examination revealed suprapubic tenderness. Computed tomography identified a bladder dome mass and a subsequent image-guided biopsy confirmed ES/PNET. The patient received eight cycles of neoadjuvant chemotherapy, which led to significant regression on post-chemotherapy magnetic resonance imaging. Partial cystectomy with 2-cm margins was performed, followed by primary bladder closure. Pathology confirmed pathological complete response, showing no viable tumor (inflammatory changes, urothelial hyperplasia, necrosis, and fibrosis). Adjuvant radiotherapy was administered, and the patient is currently completing adjuvant chemotherapy. Surveillance imaging and cystoscopy 2 months post-operatively showed no evidence of recurrent disease. Clinical discussion: The rarity of bladder ES/PNET presents a therapeutic challenge. This case aligns with emerging evidence that neoadjuvant chemotherapy can be highly effective, facilitating less radical surgery. This strategy successfully avoided radical cystectomy, thereby preventing the associated long-term complications of urinary diversion. The addition of adjuvant radiotherapy was motivated by the initial presence of extensive soft tissue invasion and borderline lymph nodes, aiming to optimize local control. Conclusion: Multimodal therapy with neoadjuvant chemotherapy followed by adjuvant chemotherapy and radiotherapy can facilitate bladder preservation in pediatric bladder ES/PNET without compromising oncological outcomes. This strategy can mitigate the long-term morbidity of radical surgery.