Snapshot A 15-month-old male is brought in to his pediatrician for routine exam. On exam, his pediatrician notices that he has no irises, consistent with aniridia. He is also found with a palpable, non-tender mass on the left side of his abdomen. On further questioning, his mother reveals that her cousin had a similar abdominal mass at a young age. The patient and his mom are referred to pediatric surgeons for further management. An abdominal CT scan is obtained. Introduction Embryonal malignancy of the kidney embryonic glomerular structure aka nephroblastoma derived from the metanephros Epidemiology Most common renal tumor of childhood Seen in otherwise healthy children < 4 years old ETIOLOGY Pathogenesis loss of function mutation of tumor suppressor genes WT1 or WT2 Risk factors family history horseshoe kidney Associated conditions WAGR syndrome Wilms tumor Aniridia Genitourinary anomalies Retardation Beckwith-Wiedemann syndrome overgrowth macrosomia macroglossia hemihyperplasia organomegaly abdominal wall defects embryonal tumors neonatal hypoglycemia neurofibromatosis Presentation Abdominal mass in previously healthy, asymptomatic child Symptoms (25-30% of children) fever hematuria dysuria constipation abdominal pain Unusual presentation of clinical emergency massive bleeding from ruptured tumor acute abdomen Physical exam palpable, painless abdominal mass does not cross midline hypertension some present with aniridia IMAGING Best initial test abdominal ultrasound Most accurate test CT with contrast Radiography or CT to detect lung metastases STUDIES Tissue diagnosis after surgical resection blastemal, epithelial, and stromal cells biopsy not indicated diagnostic confirmation with tissue from surgery Differential Diagnosis Neuroblastoma Polycystic kidney disease Other primary renal malignancies Treatment Prevention genetic counseling based on family history Standard therapy nephrectomy chemotherapy If with metastases radiation added Post-surgery screening for recurrence with abdominal ultrasound every 3 months Complications Nephropathy Hypertension Renal failure Prognosis Better prognosis with younger age Overall 5-year survival rate > 90%