Wilms tumor

Alternative names:

kidney tumor; nephroblastoma; tumor - Wilms

Definition:

A cancerous tumor of the kidney that occurs in children.

Causes, incidence, and risk factors:

Wilms' tumor is the most common intraabdominal tumor in children and the most common type of kidney tumor. The exact cause of tumor formation is unknown, but it probably develops in fetal tissue. It is associated with certain congenital defects including urinary tract abnormalities, absence of the iris (aniridia) and hemihypertrophy (enlargement of one side of the body), and shows an increased incidence among siblings and twins, which suggests a possible genetic cause. The tumor may become quite large, but usually remains encapsulated (self-enclosed). It may spread to other body tissues.

The frequency of disease occurrence is estimated to be about 1 out of 200,000 to 250,000 children. The peak incidence is at 3 years old. Rarely, the tumor may be present in adults.