Diagnosis

After an abdominal mass is identified, radiographic imaging is performed to determine the anatomic location and extent of the mass.

The diagnostic workup includes a chest x-ray and an abdominal ultrasound. The chest x-ray is done to evaluate for the presence of pulmonary metastasis. Additional studies include urinalysis, abdominal plain film, and computed tomography (Image 9.18). The urine may contain red blood cells (20% of cases) or hyaluronic acid. The abdominal x-ray may show “eggshell” calcifications. This is in contrast to the “speckled” calcifications seen in neuroblastoma and the “popcorn” calcifications seen in teratomas.

Although magnetic resonance imaging (MRI) avoids radiation exposure, it has not been shown to be superior to CT scanning in standard assessments. MRI is currently being evaluated as a method to help distinguish nephrogenic rests from WT and may be the preferred method to follow children with bilateral WT after resection.

F-fluorodeoxyglucose positron emission tomography (FDG PET) has not been fully delineated in pediatric cancers. It is recognized that FDG PET has an established role in Hodgkin lymphoma and increasingly in sarcomas in children, but its role in WT is unclear.