complex cyst which is mildly enhanced in a 9 yr old girl

Our nine year old daughter has tuberous sclerosis complex (causes tumors to grow on the vital organs of the body-typically they are benign). She has had MRI scans for a couple of years now. Last year they discovered bilateral simple cysts (typical for tsc) but only 12 months later they found a tumor that tripled in size (still less then 2 cm though) and they are now calling it complex with thin wall septa and mild enhancement. They suggested getting another MRI in 6 months but said we could move it up to 3 months which we are. Her doctors tell me that there are few pediatric cases of renal cancer and not to get too worried. How do you do that? We are scared and from what I have read it appears that if there is any enhancement evident it is RCC-is this correct? It seems like none of the medical professionals want to alarm us so they are just making it sound like an everyday occurance-are we overreacting? Also, they think we should stick with a nephrologist who is also highly knowledgable in TSC however in my opinion, TSC or no TSC, a complex cyst is a complex cyst and I want her to be treated by the best there is. After reading posts it appears that the Cleveland Clinic comes highly recommended and they also have a TSC clinic there so that should satisfied her specialists in that respect. Any thoughts would be greatly appreciated. Thanks so much.