Purpose or Case Report: Wilms tumors, also known as nephroblastomas, are overwhelmingly the most common renal tumors in children. While radiologists are abundantly familiar with the imaging appearances of these tumors, their knowledge of underlying histologic features, prognostic variables, and treatment approaches may not be equally robust. Histologically typically triphasic and containing differing proportions of blastemal, epithelial, and stromal components, the prognosis of individual subtypes differs. The “teratoid” variant of Wilms tumor contains components of differentiated tissues such as muscle, bone, cartilage, and fat. Focal and diffuse anaplasia are important histological features with diffuse anaplasia recognized as the most important prognostically unfavorable feature. In addition, there is an intermediate category of “nuclear unrest” which carries some but not all features of anaplasia. Clinical approaches differ between the two major renal tumor clinical research groups: the International Society of Paediatric Oncology (SIOP) Renal Tumor Study Group and the Children's Oncology Group (COG) Renal Tumor Group. This exhibit uses a case-based template of radiologic-pathologic correlation of different Wilms subtypes encountered at our institution, outlining treatment for individual tumor subtypes. We discuss differential diagnoses which may overlap with Wilms tumor on imaging, including nephrogenic rests, mesoblastic nephroma, malignant rhabdoid tumor of the kidney, clear cell sarcoma, and pediatric cystic nephroma (as a mimic of cystic Wilms tumor). We review Wilms tumor classification with known syndromic associations. We provide information on staging through the National Wilms Tumor Study system covering imaging and post-surgical findings. The ultimate goal is to make radiologists more effective members of the interdisciplinary tumor boards through enhancing a holistic understanding of Wilms tumor.
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