Wilms tumor is the most common type of kidney cancer in children. It typically affects children between ages 3-5 years old and presents as a unilateral tumor in the kidney, though 5% of cases are bilateral. The exact cause is unknown but genetic factors are involved. Treatment involves surgery to remove the tumor along with chemotherapy and sometimes radiation therapy. Due to advances in multidisciplinary treatment, survival rates for Wilms tumor are now around 90%.