It will be better if you could post the USG report so that it will be clear as to what the echogenic lesion is exactly. It most probably might be a calculus i.e a stone in the gall bladder.  But why the report says extending into the gall bladder. I personally feel that if it is such a large stone then even if it is asymptomatic at present you should still go ahead with surgery as the complications related to it although less likely are very serious.

Hi if there is no upper abdominal pain / post meal fullness / discomfort / upper back pain , then you don't require surgery. This is asymptomatic gall stone. In case you develop any of above symptoms them you require surgery. You can read my article on Practo- Gall bladder stone.feel free to ask any further quary.