Children's Hospital Colorado

Wilms Tumor in Children

What is a Wilms tumor?

A Wilms tumor, also known as nephroblastoma, is a malignant (cancerous) tumor that forms in the kidneys. Tumors that form in or on the kidneys are also known as renal tumors. Wilms tumors can affect both kidneys, but usually only forms in one.

At Children's Hospital Colorado, our Urologic Tumor Program has extensive experience diagnosing and treating Wilms tumor and other tumors of the kidney in kids.

What causes a Wilms tumor in kids?

There is no strong evidence showing that Wilms tumor is hereditary (passed through the genes from a parent or relative to a child). As the kidney cells are forming in the fetus, some of the cells do not grow properly and form a tumor or create conditions in which a tumor can form later. There is no known cause for a Wilms tumor.

Who gets a Wilms tumor?

The Wilms tumor is the most common type of renal tumor, affecting boys and girls equally and accounting for about 7% of all pediatric cancers. Although it's possible to find a Wilms tumor in children from birth through 15 years of age, it is more commonly found in children ages 3 to 4 and is much less common after a child reaches the age of 5. There are several rare syndromes that greatly increase the chance of having a Wilms tumor.

Syndromes associated with Wilms tumors

WAGR syndrome

WAGR is an acronym that represents the four diseases present in the syndrome: Wilms tumor, aniridia, genitourinary malformations and retardation. Aniridia is a disease that results in the absence of the iris, the colored part of the eye. A genitourinary malformation is a defect that can affect the kidneys, urinary tract, scrotum, penis, testicles, clitoris and ovaries. WAGR syndrome is linked to the loss or inactivation of the WT1 gene on chromosome 11, which is a gene that usually controls cell growth and suppresses the growth of tumors.

Denys-Drash syndrome

Associated with kidney failure as well as genitourinary malformations (a defect that can affect the kidneys, urinary tract, scrotum, penis, testicles, clitoris and ovaries), this syndrome is also linked to the loss or inactivation of the WT1 gene on chromosome 11.

Beckwith-Wiedemann syndrome

Also due to an abnormality of chromosome 11, this syndrome is linked to an overactive gene called IGF2, which controls cell growth. Characterized by numerous abnormalities, symptoms of Beckwith-Wiedemann syndrome include:

  • Higher than average birth weight
  • An enlarged tongue, spleen and liver
  • Asymmetric (uneven) growth of the body
  • Malformations around the ear
  • Omphalocele (defects on the abdominal wall near the navel)
  • Tumors on the liver and adrenal glands
  • Low blood sugar in the neonatal period