Pathophysiology
Clinical meaning
Wilms tumor (nephroblastoma) is the most common primary renal malignancy in children, typically diagnosed between 2 and 5 years of age. It arises from embryonic kidney tissue (metanephric blastema) that fails to differentiate normally during fetal development, resulting in persistent nephrogenic rests that can undergo malignant transformation. The tumor originates within the renal parenchyma and can grow to a very large size before detection because the retroperitoneal space accommodates significant expansion. Wilms tumor is classified based on histology into favorable histology (approximately 90% of cases, with a cure rate exceeding 90%) and unfavorable or anaplastic histology (approximately 10% of cases, associated with a poorer prognosis due to resistance to chemotherapy). The tumor may be unilateral (affecting one kidney, approximately 93% of cases) or bilateral (affecting both kidneys, approximately 5-7% of cases). Several genetic mutations are associated with Wilms tumor, including mutations in the WT1 gene on chromosome 11p13 and the WT2 gene on chromosome 11p15.5. Wilms tumor is also associated with congenital anomalies and syndromic conditions including WAGR syndrome (Wilms tumor, Aniridia, Genitourinary anomalies, and intellectual disability), Beckwith-Wiedemann syndrome (macroglossia,...