This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Childhood Tumors, Subject name: Pediatrics
Most common tumor of kidney in children is: 
Select and explain. 
A. Wilms' tumor, B. Neuroblastoma, C. Polycystic kidney disease, D. Renal cell carcinoma
A: Wilms' tumor
Answer: A: Wilms' tumor 
Explanation: a. Wilms' tumor(Ref: Nelson's 20/e p 2464-2465)Wilms' tumor (WT), also known as nephroblastoma, is the most common primary malignant renal tumor of childhood;It is the second most common malignant abdominal tumor in childhood.The most common sites of metastases from Wilms tumor are the lungs, regional lymph nodes, and liver.