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Definition of Wilms tumor:
A disease in which malignant (cancer) cells are found in the kidney, and may spread to the lungs, liver, or nearby lymph nodes. Wilms tumor usually occurs in children younger than 5 years old.
Wilms tumor and other childhood kidney tumors are diseases in which malignant (cancer) cells form in the tissues of the kidney.
Wilms tumor and other kidney tumors are diseases in which malignant (cancer) cells are found in the kidney. In Wilms tumor, one or more tumors may be found in one or both kidneys. There are two kidneys, one on each side of the backbone, above the waist. Tiny tubules in the kidneys filter and clean the blood, taking out waste products and making urine. The urine passes from each kidney through a long tube called a ureter into the bladder. The bladder holds the urine until it is passed from the body.
Anatomy of the female urinary system showing the kidneys, adrenal glands, ureters, bladder, and urethra. Urine is made in the renal tubules and collects in the renal pelvis of each kidney. The urine flows from the kidneys through the ureters to the bladder. The urine is stored in the bladder until it leaves the body through the urethra.
Wilms tumor may spread to the lungs, liver, or nearby lymph nodes.
Nephroblastomatosis is a condition in which abnormal tissue grows on the outer part of one or both kidneys. Children with this condition are at risk for developing a type of Wilms tumor that grows quickly. Frequent follow-up testing is important for at least 7 years after the child is treated.
Other kidney tumors
Other childhood kidney tumors, which are diagnosed and treated in different ways, include:
- Clear cell sarcoma of the kidney is a type of kidney tumor that may spread to the lung, bone, brain, and soft tissue.
- Rhabdoid tumor of the kidney is a type of kidney cancer that occurs mostly in infants and young children. It is often advanced at the time of diagnosis. Rhabdoid tumor of the kidney grows and spreads quickly, often to the lungs and brain.
- Neuroepithelial tumors of the kidney are rare and usually occur in young adults. They grow and spread quickly.
- Desmoplastic small round cell tumor of the kidney is a rare soft tissue sarcoma.
- Cystic partially differentiated nephroblastoma is a very rare type of Wilms tumor made up of cysts.
- Renal cell carcinoma is rare in children or in adolescents younger than 15 years of age. However, it is much more common in adolescents between 15 and 19 years of age. Renal cell carcinomas can spread to the lungs, bones, liver, and lymph nodes.
- Congenital mesoblastic nephroma is a tumor of the kidney that is usually diagnosed within the first year of life and can usually be cured. One type of congenital mesoblastic nephroma may appear on an ultrasound exam before birth or may occur within the first 3 months after the child is born. Congenital mesoblastic nephroma occurs more often in males than females.
- Primary renal synovial sarcoma is a rare tumor of the kidney and is most common in young adults.
- Anaplastic sarcoma of the kidney is a rare tumor that is most commonly found in children or adolescents younger than 15 years of age. Anaplastic sarcoma of the kidney often spreads to the lungs, liver, or bones. There is no standard treatment for anaplastic sarcoma.
Having certain genetic syndromes or birth defects can increase the risk of Wilms tumor.
Anything that increases the risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn't mean that you will not get cancer. Talk to your child's doctor if you think your child may be at risk.
Wilms tumor may be part of a genetic syndrome that affects growth or development. A genetic syndrome is a set of symptoms or conditions that occur together and is usually caused by abnormal genes. Certain birth defects can also increase a child's risk for developing Wilms tumor. The following genetic syndromes and birth defects have been linked to Wilms tumor:
- WAGR syndrome (Wilms tumor, aniridia, abnormal genitourinary system, and mental retardation).
- Beckwith-Wiedemann syndrome.
- Idiopathic hemihypertrophy (abnormally large growth of one side of the body or a body part).
- Denys-Drash syndrome.
Children with these genetic syndromes and birth defects should be screened for Wilms tumor every three months until at least age 8. An ultrasound test of the abdomen may be used for screening. Children with Beckwith-Wiedemann syndrome or hemihypertrophy are also screened for liver and adrenal tumors that are linked to these genetic syndromes. A test to check the alpha-fetoprotein level in the blood and an ultrasound of the abdomen are done until age 4 years. An ultrasound of the kidneys is done after age 4 years.
Some children develop Wilms tumor in both kidneys. These often appear when Wilms tumor is first diagnosed, but a Wilms tumor may also occur in the second kidney after the child is successfully treated for Wilms tumor in one kidney. A second tumor is much more likely to develop in the other kidney when a child's first Wilms tumor is diagnosed before age 12 months or when embryonic cells remain in the kidney.
Children at risk for developing a second Wilms tumor in the other kidney should be screened for Wilms tumor every three months for two to six years. An ultrasound test of the abdomen may be used for screening.
Having certain conditions may be associated with renal cell carcinoma.
Renal cell carcinoma may be related to the following conditions:
- Von Hippel-Lindau disease (an inherited condition that causes abnormal growth of blood vessels). Children with Von Hippel-Lindau disease should be checked yearly for renal cell carcinoma with an ultrasound of the abdomen or MRI (magnetic resonance imaging) beginning at age 8 to 11 years.
- Tuberous sclerosis (an inherited disease marked by noncancerous fatty cysts in the kidney).
- Familial renal cell carcinoma (an inherited condition that occurs when certain changes in the genes that cause kidney cancer are passed down from the parent to the child).
- Renal medullary carcinoma (a rare kidney cancer that grows and spreads quickly).
- Hereditary leiomyomatosis (a disorder that increases the risk of having cancer of the kidney, skin, and uterus).
- Second cancers (renal cell carcinoma may be found in patients several years after treatment for neuroblastoma).
- Signs of Wilms tumor and other childhood kidney tumors include a lump in the abdomen and blood in the urine.
These and other signs and symptoms may be caused by kidney tumors or by other conditions. Check with a doctor if your child has any of the following:
- A lump, swelling, or pain in the abdomen.
- Blood in the urine.
- Fever for no known reason.
Tests that examine the kidney and the blood are used to detect (find) Wilms tumor and other childhood kidney tumors.
The following tests and procedures may be used:
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
- The number of red blood cells, white blood cells, and platelets.
- The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
- The portion of the blood sample made up of red blood cells.
- Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.
- Liver function test: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by the liver. A higher than normal amount of a substance can be a sign that the liver is not working as it should.
- Renal function test: A procedure in which blood or urine samples are checked to measure the amounts of certain substances released into the blood or urine by the kidneys. A higher or lower than normal amount of a substance can be a sign that the kidneys are not working as they should.
- Urinalysis: A test to check the color of urine and its contents, such as sugar, protein, blood, and bacteria.
- Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. An ultrasound of the abdomen is done to diagnose a kidney tumor.
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
- Abdominal x-ray: An x-ray of the organs inside the abdomen. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
- Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. Whether a biopsy is done depends on one or more of the following:
- Cancer is in one or both kidneys.
- Imaging tests clearly show the cancer.
- The patient is on a clinical trial.
A biopsy may be done before treatment, after surgery to remove the tumor, or after chemotherapy to shrink the tumor.
Wilms tumor and other childhood kidney tumors are usually diagnosed and removed in surgery.
Once a kidney tumor is found, surgery is done to find out whether or not the tumor is cancer. If the tumor is only in the kidney, the surgeon will remove the whole kidney (nephrectomy). If there are tumors in both kidneys or if the tumor has spread outside the kidney, a piece of the tumor will be removed. In any case, a sample of tissue from the tumor is sent to a pathologist, who looks at it under a microscope to check for signs of cancer.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options depend on the following:
- How different the tumor cells are from normal kidney cells.
- The stage of the cancer.
- The type and size of the tumor.
- The age of the child.
- Whether the tumor can be completely removed in surgery.
- Whether the cancer has just been diagnosed or has recurred (come back).
- Whether there are any abnormal chromosomes or genes.
- Whether the patient is treated by pediatric experts with experience in treating patients with Wilms tumor.
Wilms tumor is rare in adults.
Wilms tumor in adults is harder to cure than in children. When a Wilms tumor is found, tests should include checking lymph nodes for cancer.
For more information on Wilms Tumor and Other Childhood Kidney Tumors click here
This link is to the National Cancer Institute (NCI) cancer website in the United States. There may be references to drugs and clinical trials that are not available here in Australia.
For information about clinical trials that are available in Australia click here