Health Encyclopedia

Wilms tumor

Definition

Wilms tumor is a cancerous tumor of the kidney. This tumor occurs in children.

Alternative Names

Nephroblastoma; Kidney tumor

Causes, incidence, and risk factors

Wilms tumor is one of the most common childhood tumors of the abdomen, and the most common type of kidney tumor. The exact cause of this tumor in most children is unknown.

The tumor is associated with certain birth defects, including urinary tract abnormalities, absence of the iris (aniridia), and hemihypertrophy (enlargement of one side of the body). It is more common among some 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, especially the lungs.

The disease is estimated to occur in about 1 out of 200,000 to 250,000 children. The peak time of occurrence is at 3 years old, and Wilms tumor is rare after the age of 8 years.

Symptoms

Abdominal pain
Swelling in the abdomen (abdominal hernia or mass)
Blood in the urine (occurs in less than 1/4 of children)
Fever
Loss of appetite
Nausea
Vomiting
General discomfort or uneasiness (malaise)
High blood pressure
Constipation
Increased growth on only one side of the body (hemihypertrophy)

Note: Abnormal urine color may also be associated with this disease. A missing iris of the eye (aniridia) is a birth defect that is sometimes associated with Wilms tumor.

CAUTION: Avoid palpation (prodding or pushing) of the abdomen, and use care during bathing and handling to avoid injury to the tumor site.

Signs and tests

Special emphasis is placed on the history and physical exam -- looking for a family history of cancer and for associated birth defects in the child. The physical examination reveals an abdominal mass. High blood pressure may also be present.

Tests include:

CBC (may show anemia)
BUN
Creatinine
Creatinine clearance (may be decreased)
Urinalysis (blood or protein in urine)
Abdominal ultrasound
Abdominal x-ray
Chest x-ray (may demonstrate metastasis)
Intravenous pyelogram (distortion of the kidney)
CT scan of the abdomen (abdominal mass arising from kidney)

Other tests may be required to determine if the tumor has spread.

Treatment

Clinical staging of the tumor is done to determine the extent of the tumor and to maximize the effectiveness of treatment plans. Surgical exploration and removal of the tumor is scheduled as soon as possible.

Regional lymph nodes, abdominal organs, and other tissues are examined and removed if the tumor has spread to those areas. Radiation therapy and chemotherapy will often be started after surgery, depending on the stage of the tumor.

Expectations (prognosis)

With treatment, the disease has a high cure rate. Children with a localized tumor have a 90% cure rate when treated with surgery and chemotherapy; or with surgery, radiation, and chemotherapy combined.

Complications

Spread of the tumor to the lungs, liver, bone, or brain is the most worrisome complication. High blood pressure and kidney damage may occur as the result of the tumor or its treatment. Removal of Wilms tumor that is present in both kidneys may leave the patient with borderline kidney function.

Calling your health care provider

Call your health care provider if you discover an abdominal mass in your child's abdomen, blood in the urine, or other symptoms suggestive of Wilms tumor.

Call your health care provider if symptoms worsen or new symptoms develop during or after treatment for Wilms tumor, particularly cough, chest pain, weight loss, or persistent fevers.

Prevention

For children with a known high risk of Wilms tumor, screening with ultrasound of the kidneys may be recommended.

Review Date:5/26/2006
Reviewed By:Rita Nanda, MD, Department of Medicine, Section of Hematology/Oncology, University of Chicago Medical Center, Chicago, IL. Review provided byVeriMed Healthcare Network.

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