HISTOLOGY
Nephroblastoma (Wilms tumour). The tumour consists predominantly of stroma (60%) with areas of skeletal muscle differentiation. Scattered through the stroma are areas of blastema (30%) some of which are associated with tubule formation (10%). There is no evidence of anaplasia. Necrosis is present. The tumour infiltrates into the renal hilar adipose tissue but does not involve the venous or lymphatic vascular spaces.