Definition

Wilms tumor is a type of kidney cancer. It’s mainly found in children. Most of the time, it’s found in one kidney, not both.

The Kidneys

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Causes

Before birth, some of kidney cells don’t mature like they’re supposed to. After the baby is born, clusters of these cells are still there. If they do not mature within 3 to 4 years, they may grow without control or order. A large mass of these cells may grow into a Wilms tumor.

Risk Factors

The chances of Wilms tumor are higher for:

• Getting a certain gene from a parent that isn’t normal
• Having someone in the family with same problems
• Certain syndromes such as:
  • WAGR—a syndrome that includes:
    • W ilms tumor
    • A niridia—The colored part of the eye may be partly or fully missing.
    • G enitourinary abnormalities
    • R etardation
  • Beckwith-Wiedemann syndrome—Larger than normal tongue and organs. One arm or leg may be larger than the other.
  • Perlman syndrome—Large size before birth. May also have Wilms tumor. These may involve other organs and intellectual problems.
  • Denys-Drash syndrome—Male genitals are not present or completely formed.
  • Hemihypertrophy—One side of the body larger is than the other.
  • Other defects on chromosome 11.

Many children with Wilms tumors don’t have these problems. The cause of their kidney cells not maturing is unknown.

Symptoms

Wilms tumor may be first felt as a large mass in the belly. Other problems may include:

• Stomach pain
• Fever
• Blood in the urine
• Loss of hunger

Wilms tumors may grow larger without causing pain or other problems.

Diagnosis

You will be asked about your child’s symptoms and health history. During a physical exam, the doctor will look for signs of the syndromes listed above. These may point to a Wilms tumor.

• Blood tests
• Testing for certain genes
• Urine tests
• Biopsy —tumor samples may be taken during surgery (not always needed)
• Imaging tests such as:
  • Abdominal ultrasound
  • CT scan
  • Chest x-rays

Treatment

Wilms tumor can be cured in most children. The plan depends on the stage of cancer. Many times, different methods are used. These may include:

Prevention

If you have Wilms tumor in your family, talk to your doctor about genetic testing before you start your own family. If your child is at high risk, talk to their doctor about screening. This may help find tumors early.