A 3-year-old child has become less active over the past 2 months. On physical examination an abdominal mass is palpable on the left. A urinalysis shows hematuria. Radiographic studies show an 8-cm mass in the left retroperitoneal space. The mass is excised and on microscopic examination shows a triphasic combination of blastemal, stromal, and epithelial cell types. The child is doing well 10 years later. Which of the following most likely related to the pathogenesis of this child's neoplasm?

Nephrogenic rests can be found in the renal parenchyma adjacent to a Wilms tumor. They are presumed precursor lesions because they may share genetic alterations with the adjacent Wilms tumor. There is an increased risk of developing Wilms tumors in the contralateral kidney if such rests are present. Anaplasia in Wilms tumor suggests a poor prognosis, but overall the cure rate is 90%. Ganglion cells and pseudo rosettes are features of neuroblastoma. Long-term survivors of Wilms tumor are at increased risk for another malignancy, including a sarcoma, but the sarcoma is not part of the original tumor.