Wilms Tumor

Posted September 14, 2022 by Anusha ‐ 3 min read

A Wilms tumor (also called a nephroblastoma) is the most common kidney cancer in children. Most children with it have a tumor on one kidney, but about 5% get a tumor on both.

Causes of Wilms Tumor

  • All cancers happen when cells in your body start to grow out of control.

  • If your child has a Wilms tumor, their kidney cells didn’t grow like they should have.

  • Instead, they turned into cancer cells.

  • Most of the time, this is because of a random change in a gene.

  • Rarely, it’s because of gene changes handed down from a parent.

Symptoms of Wilms Tumor

  • Belly pain

  • Swelling in their belly

  • A growth that you can see or feel in their belly

  • Fever

  • Nausea

  • Lack of appetite

  • High blood pressure

  • Blood in their pee

  • Constipation

  • Shortness of breath

Types of Wilms Tumor

There are two kinds of Wilms tumors, divided by how the cells look under a microscope.

Favorable histology

More than 9 out of 10 Wilms tumors fall into this group. It means there isn’t a lot of difference among the cancer cells. Children with this type have a good chance of being cured.

Unfavorable or anaplastic histology

This type has a variety of deformed cancer cells. It can be much harder to cure.

Diagnosis of Wilms Tumor

Your child’s medical appointment will probably include:

  • A physical exam and medical history. Your doctor will ask about the symptoms and whether cancer or urinary tract problems run in your family.

  • A blood test to check how well your child’s kidneys and liver are working, their red and white blood cells, and their blood clotting.

  • A urine test to look for blood

  • Imaging tests like an ultrasound, MRI, or CT scan of your child’s belly



If your doctor operates, they may do one of these procedures:

Partial nephrectomy

This removes the tumor and some healthy tissue around it.

Radical nephrectomy

This removes the affected kidney, the ureter (the tube that carries pee away from the kidney), the adrenal gland on top of the kidney, and nearby tissue.

Removal of both kidneys

In some cases, the doctor will need to take out both kidneys. Your child would then need to have dialysis, using a machine to filter waste out of their blood. Once they’re healthy enough, they might have a kidney transplant.


Certain medications can fight or kill cancer cells inside your child’s body. Most children who have Wilms tumors will get chemo at some point during treatment. These drugs can also affect healthy cells, leading to side effects including:

  • Hair loss

  • Fatigue

  • Mouth sores

  • Loss of appetite

  • Nausea and vomiting

  • Diarrhea or constipation

  • Bruising or bleeding easier than usual

  • Higher chances of infection


  • Strong radiation can also kill cancer cells.

  • A machine focuses it onto the cancer.

  • Doctors tend to use radiation for tumors that are stage III and above.

  • But it can also have short-term and long-term side effects, including tissue damage, so they’ll use as little as possible.

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