Snapshot A 2-year-old girl is brought to the emergency room after her mother discovers a mass in the girl's abdomen while bathing. The girl occasionally cries when urinating, but is otherwise asymptomatic, without any abdominal pain. On exam, she is found to be hypertensive. There is a palpable, non-tender mass on the right side, which does not cross the midline. A chest radiograph is ordered to assess for lung involvement. Introduction Embryonal malignancy of the kidney embryonic glomerular structure aka nephroblastoma Epidemiology most common renal tumor of childhood seen in otherwise healthy children < 4 years old Pathogenesis loss of function mutation of tumor suppressor genes WT1 or WT2 Wilms tumor 1 gene and Wilms tumor 2 gene 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 Presentation Abdominal mass in previously healthy, asymptomatic child Symptoms fever hematuria dysuria constipation abdominal pain Physical exam palpable, painless abdominal mass does not cross midline hemihypertrophy of kidney due to increased vascular demands hypertension due to renin secretion some present with aniridia Evaluation Abdominal ultrasound Radiography or CT to detect lung metastases Tissue diagnosis after surgical resection Differential Diagnosis Neuroblastoma Polycystic kidney disease Other primary renal malignancies Treatment Standard therapy nephrectomy chemotherapy Post-surgery screening for recurrence with abdominal ultrasound every 3 months Prognosis, Prevention, and Complications Prognosis better prognosis with younger age overall 5-year survival rate > 90% Prevention genetic counseling based on family history Complications nephropathy hypertension renal failure