Most patients with Wilms tumor have an asymptomatic abdominal mass, but potentially life-threatening conditions include hypertension, gross hematuria, and an acute abdomen Current Evidence There are several different causes of renal tumors in children, some malignant and some benign Wilms tumor, the most common pediatric renal tumor, arises from embryonic renal blastemal cells (see Fig 98.2 ) Overgrowth syndromes such as Beckwith–Wiedemann, Soto syndrome, hemihypertrophy, and Denys–Drash syndrome predispose to embryonal tumors such as Wilms’ There are 500 cases of Wilms’ diagnosed annually in United States with peak incidence between the ages of and Eighty percent of cases are diagnosed by age