Wilms Tumor : Post-Chemotherapy

National Wilms Tumor Study (NWTS) group protocol recommends primary resection of the tumor followed by additional therapy based on the tumor stage and favorable vs unfavorable histology. SIOP (Societe Internationale D'oncologie Pediatrique) - a European group recommends pre-operative chemotherapy for all stages followed by resection. The post-chemotherapy tumors are evaluated for response and subdivided into 3 risk categories : low risk, intermediate risk, and high risk. This image shows a few residual tubules surrounded by a zone of fibrosis and hemorrhage with scattered inflammatory cells.