Wilms' Tumor

Wilms' tumor is a cancerous tumor of the kidney that occurs in children. It is one of the most common tumors of the abdomen in children, and its exact cause is unknown. It is associated with certain birth defects including urinary tract abnormalities, absence of the iris and hemihypertrophy (enlargement of one side of the body). It is more common among siblings and twins, which suggests some genetic cause. The tumor may become quite large, but usually remains encapsulated (self-enclosed). It may spread to other areas of the body, like the lungs. The peak time of occurrence is three years of age, and it is rare after age eight. 

Symptoms may include abdominal pain, blood in urine, swelling in the abdomen, fever, loss of appetite, nausea, vomiting, general discomfort or tiredness, high blood pressure, constipation or abnormal urine color. 

Parents should avoid pressure on the abdomen and be careful while bathing their children and engaging in other activities with them. 

Tests ordered by the doctor to diagnose the disease include blood tests, urine tests, X-rays and CT scans, and an intravenous pyelogram (IVP), which involves injecting dye into the bloodstream and then taking X-rays to see where the dye goes. 

The doctor will want to stage the tumor to see how advanced it is and to determine a plan of treatment. Surgical exploration and removal of the tumor is scheduled as soon as possible. Sometimes it's necessary to remove the entire kidney if it is damaged. 

With the patient under general anesthesia, the surgeon makes an incision on the abdomen or on the side with the affected kidney. The tissue around the kidney that is infected will be cut away and removed. If the kidney must be removed, the surgeon will cut away the tubes connecting the kidneys to the bladder and remove the kidney. The incision will then be closed. This can be done laparoscopically, through tiny incisions, in some cases. 

The patient is given IV fluids and pain medication after surgery. The surgery is often painful because of the positioning necessary during surgery. The patient's blood pressure and urine output are monitored carefully because these functions are controlled in some way by the kidneys. Most likely, a urinary catheter will be placed to drain urine temporarily. Patients do very well with only one kidney. 

As with any surgery, there is the possibility of breathing problems related to anesthesia, blood clots or hemorrhage. 

The physician also will talk to specialists in radiation therapy and medical oncology to see if radiation therapy and chemotherapy are necessary. 

With treatment, this disease has a high cure rate. Children with a tumor that hasn't spread have a 90% cure rate when treated with surgery and chemotherapy or surgery, chemotherapy and radiation. 

The most feared complication is spread of the tumor to the lung, bones, brain and liver. High blood pressure and kidney damage may occur as the result of the tumor or its treatment.

For an appointment with a Washington University pediatric urologic surgeon, call (314) 454-6034.

More information on Wilms' tumor:

National Cancer Institute CancerGov Web Page on Wilms' Tumor