Wilms tumor, typically a solid pediatric kidney cancer, can rarely appear cystic, mimicking cystic nephroma or cystic partially differentiated nephroblastoma. We report a 20-month-old boy presented with a right abdominal mass, hypertension, and poor appetite. MRI showed a cystic renal tumor, requiring primary nephrectomy without chemotherapy. Postoperative histology revealed a cystic Wilms tumor, necessitating further treatment. This case highlights the diagnostic challenge of cystic renal tumors and emphasizes the importance of histopathology in guiding management. Surgical and chemotherapeutic strategies must be carefully individualized based on clinical and imaging findings.

© 2025 The Authors. Published by Elsevier Inc.