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Wilms tumor (kidney tumors)

A Wilms tumor (nephroblastoma) is a malignant tumor in or near the kidney. This type of tumor only occurs in children. The tumor is usually in one kidney, sometimes (3-5%) in both kidneys. In the Netherlands, 20 to 25 children a year are diagnosed with a Wilms tumor. Most children are under five years of age.

Symptoms of this disease

Children with a kidney tumor often have no symptoms for a long time. They seldom have pain. Usually a convex stomach shape is the first sign that something is wrong. Your child may urinate blood or complain about abdominal pain. The symptoms are usually so vague that it is only after you have realized that your child was not OK. Only once the diagnosis has been made will you understand why your child was languid, tired, listless, nauseous or feverish and why he or she did not have an appetite.

How do we make the diagnosis?

We make the diagnosis by means of an ultrasound scan and an MRI scan of the abdomen. We also take an X-ray and a CT scan of the lungs. This examination is necessary to see in which kidney the tumor is located and whether the tumor has spread to other organs, such as the liver or the lungs.

If we are not yet sure of the diagnosis, we will carry out an additional tissue assessment. There are tumors that resemble Wilms tumors, such as clear cell sarcomas and rhabdoid tumors. In addition, it is important to exclude a neuroblastoma (adrenal tumor). This can be done simply by examining urine.

Treatment of a Wilms tumor

We treat children with a Wilms tumor in accordance with international treatment protocols. We look at the stage the tumor is in. The treatment varies for each stage. The treatment always consists of chemotherapy and surgery to remove the kidney affected with a tumor. Sometimes radiation is also necessary.