My 20 year old BIL has one. It was only discovered about a year ago when his vision started going a bit funny. Turns out it was the size of a golf ball and pushing on his optic nerve. They aren't exactly sure how long he's had it for but it pretty obvious it hindered his development in some way. Once he started getting it treated it was like he suddenly went through puberty. His is being treated with drugs to shrink it, no surgery...by a neurologist I believe.