Was told there is numerous cysts and a ascitic homogenous renal mass on the right lower renal pole was 6mm 6mths ago, now 2.5cm. Have urology appt next week. What is the possibility of diagnosis to expect?

I don't know what diagnosis to tell you to expect as I am not a doctor. That being said, just by the wording suggests besides the numerous cysts you have a mass or tumor present that has grown in size. I would suggest writing your questions down that you want to ask your doctor so you don't forget them. Good luck to you.