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What is Abdominal ultra-sonography in a 3 year old boy show a solid circumscribed hypoechnoic renal mass. Most likely diagnosis is - and explain in detail?
Amongst the given options only Wilms tumor is common at 3 years of age :-
	 Wilm's tumor                  → young children (mean 3 years)
	Mesoblastic nephroma     → < 1 year
	Renal cell carcinoma        → > 40 years
	Oncocytoma                    → 25-95 years (mean 65)