Anyone else have a mass on an Atrophic Kidney?

My right kidney is atrophic (about half the size of the Left). The Urologist believes it's only functioning about 5%. Because the left is a little larger than average, he believes it's been that way my whole life since that only happens when the other one never really worked. Anyhow, the mass started on the lower pole of my atrophic kidney and has grown up it longwise.  It remained 3x3 across the bottom and it's almost as long as the entire kidney now- 4.5cm. He said he's never seen one grow that way before.  I'm curious if my recovery might be a little easier because I have already relied on just one kidney and if anyone else has had a similar situation? 

Thanks!