Epidermoid brain cyst, should I live it alone?

I have a 12 years old daughter. She was diagnosed with Epidermoid cyst in the brain back in 2001. Took her to the Neurosurgeon at Miami Children Hospital and told me to live it alone. They said that it did not seems to be of  a concern and to live it alone. Since that finding back in 2001 I  take her every 2-3 years for a CT and MRI for follow up.. Everything seems stable. Last test, a couple of weeks a go, the doctors told me it even  have shrunk in size.
The doctor told me I do not need to do  anymore tests unless she start experiencing any symptoms, My concern is that that cyst or whatever it is may develop into something bad. What should I do? Should I forget about it? or insist on cheking on her every 3 years. please help!!!
momsypomsy