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Anaplastic Wilms’ Tumor
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Unfavorable histology found in 4 to 5% of NWTS and
SIOP studies
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Uncommon in infants, but found in about 10% of
patients > 5 years of age
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Anaplasia refers to significant enlargement of nuclei
in stromal, blastemal or epithelial components to at
least 3X, hyperchromatism of enlarged nuclei and
multiple mitotic figures