Bilateral Wilms' tumor with anaplasia: lessons from the National Wilms' Tumor Study

Core needle biopsy did not identify anaplasia in 7 of 7 children. Open biopsy or partial/complete nephrectomy identified anaplasia at initial diagnostic procedure in 10 of 18 children. Twenty of 24 patients at final tissue diagnosis had discordant pathology between the 2 kidneys. Earlier interval incisional biopsy or resection may identify anaplastic histology and limit the duration of chemotherapy targeted to favorable histology for children with bilateral Wilms' tumor and anaplasia.