If your son's gyne is stable for over two years, it is unlikely that it will disappear spontaneously. I have operated on many youngsters, from age 12 - 18, and not one has had a recurrence of his gyne after surgery.
But the youngster must be motivated as well -- one would not want to push him into an operation. I often meet with the youngster alone -- with the parents asked to step outside -- in order to assess the maturity of the youngster and his motivation for surgery. If either of those qualities makes me doubtful, I will always suggest waiting a bit longer.
On the other hand, some of the happiest notes that I have received are from the youngster's parents who have stated that we have given their son's life back to him.
Dr Jacobs