This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Anatomy
Presence of nephroblastomatosis in a biopsy specimen from Wilm's tumor of left kidney indicates high possibility of 
Select and explain. 
A. Denys-Drash syndrome, B. Mutation in insulin like growth factor, C. Increased risk of tumor in right kidney, D. Lymph node metastasis
C: Increased risk of tumor in right kidney
Answer: C: Increased risk of tumor in right kidney 
Explanation: Presence of nephrogenic rests (nephroblastomatosis) in resected specimen indicates an increased risk of developing Wilm's tumor in contralateral kidney. Nephrohlastomatosis also k/a "nephrogenic rests" or nodular renal blastema, refer to the abnormal persistence of embryonal renal tissue. These are supposed to be precursor lesions of Wilm's tumor. These are seen in renal paraenchyma adjacent to tumors in approx. 25% to 40% of unilateral and 100% of bilateral tumors. Presence of nephrogenic rests in resected specimen indicates an increased risk of developing Wilm's tumor in contralateral kidney. So these patients will require frequent and regular radiological surveillance with CT scan for many years. Ref : Nelson Pediatrics 18/e p2140-2143