The doctor will take a complete medical history and give the child a physical examination. After the physical exam, an abdominal ultrasound, which uses sound waves to create images, is usually performed to view the shape of the kidney and to detect whether tumor exists in one or both kidneys.
The doctor may perform a computed tomography (CT) scan, allowing the kidneys to be seen more clearly. In CT imaging, a scanner moves around the body taking hundreds of X-ray images, which a computer then combines to make image of "slices" or cross-sections of the inside of the body. Sometimes a special dye is injected to help provide better detail.
A magnetic resonance imaging (MRI) scan, a diagnostic test that uses magnetic waves to create pictures, may also be performed.
The definitive diagnosis is made at surgery, when the surgeon will take a small piece of tumor tissue for examination under a microscope.
At this time, the pathologist will determine what type of Wilms' tumor the patient has - unfavorable histology, which comprise about 5 percent of all such tumors, or favorable histology, which make up the remaining 95 percent. In unfavorable histology tumors, the nucleus of the cancer cells is unusually large or deformed, and includes diffuse anaplastic (cells in an immature form) and clear cell sarcoma of the kidney.
This type of tumor is more difficult to cure than those with a favorable histology.
Chest and bone X-rays may also be taken to see if the cancer has spread to other parts of the body. The doctor may also perform a bone scan to detect metastases. In this procedure, the physician injects small amounts of a radioactive material (a bone-seeking nuclide, a type of atom) into a vein. The substance collects in the area of bone where there is "activity" or tumor growth and gives off radiation, which is detected by radioactive-sensitive cameras.
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