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. Treatment-induced changes include coagulative necrosis (shown here) and replacement of tumor with zones of fibrosis and hemosiderin-laden macrophages.