Congenital Wilms Tumor in a 20-day-old Neonate: Diagnostic Challenges and Management following Refusal of Adjuvant Chemotherapy

Abstract

Nephroblastoma, or Wilms tumor, is the most common pediatric renal malignancy, typically affects children aged 1–4 years yet, is rarely diagnosed in neonates. A 20-day-old male neonate presented with a progressively enlarged abdominal mass. He was born through Caesarean section due to polyhydramnion. Physical examination revealed a firm, tender, fixed mass with well-defined borders (5 cm × 4 cm), extending from the left hypochondrium to the epigastrium. Abdominal ultrasound demonstrated heterogeneous solid lesion from the upper to mid pole of the left kidney. Contrast-enhanced abdominal computed tomography scan revealed a claw sign suggestive primary renal tumor. Histopathology and immunohistochemistry confirmed nephroblastoma with predominant mesenchymal and blastemal components, WT1 positivity, and Ki-67 expression in 10%–20% of tumor cells. The patient underwent primary nephrectomy, but the family declined adjuvant chemotherapy. Congenital Wilms tumor should be considered in the differential diagnosis of neonates with abdominal masses. The favorable short-term outcome observed in this patient should not be interpreted as evidence that surgery alone is adequate treatment but rather highlights the importance of individualized follow-up when standard therapy cannot be completed.