Figure 4a. (a) Photomicrograph (original magnification, x100; hematoxylin-eosin stain) of a section through the mass shows multiple neoplastic cells, which are oval to irregular in shape and have hyperchromatic nuclei. The tumor cells are composed predominantly of blastemal and tubular elements. (b) Photomicrograph obtained at a higher power (original magnification, x200; hematoxylin-eosin stain) shows areas of abundant mitoses and apoptotic figures, findings consistent with anaplasia. (c) Photomicrograph (original magnification, x40; hematoxylin-eosin stain) of a different section through the mass shows small islands of tumor tissue within and beyond a thin fibrous tumor capsule.