Adult Wilms tumor revealed after radical nephrectomy for a renal mass initially suspected to be clear-cell renal cell carcinoma: a case report.

INTRODUCTION: Nephroblastoma is the most common malignant renal neoplasm in children but remains exceptionally rare in adults. Compared with pediatric cases, adult Wilms tumor (AWT) often presents greater diagnostic challenges and is associated with larger tumor volumes and more advanced disease at diagnosis, contributing to poorer prognoses. Consequently, adults with Wilms tumor have significantly worse outcomes than pediatric patients. Because of the limited number of reported cases, no standardized management algorithm for adults has been established; current treatment is largely based on pediatric guidelines. To date, no optimal, universally accepted therapeutic strategy has been established, and further studies with long-term follow-up are needed. CASE REPORT: We report the case of an adult patient who was preoperatively suspected of having clear cell renal cell carcinoma and subsequently underwent a radical nephrectomy. However, postoperative histopathological examination confirmed the diagnosis of nephroblastoma. The patient subsequently received multimodal treatment according to the Children's Oncology Group (COG) EE-4A regimen. At 1 year after completion of treatment, the patient was asymptomatic and had a good performance status. Contrast-enhanced computed tomography of the chest, abdomen, and pelvis showed no evidence of residual or recurrent disease, suggesting a favorable treatment response. CONCLUSION: This report provides a comprehensive overview of the epidemiology, diagnostic approaches, therapeutic strategies, and prognostic determinants of adult Wilms tumor (AWT), aiming to enhance clinicians' awareness of and ability to manage this exceptionally rare malignancy.