Ophelia- I'm trying to understand what you are describing- and I think you mean that the foreskin is still attached to the corona of the glans (the ridge between the head and the shaft) except at one spot- where it the seperation makes the appearance of a hole because you are looking behind the ridge. Did I understand correctly? Also I don't know what age your son is.
As long as it's not bothering him- I don't think you need to worry about it- you may want to bring it up with a Dr. (with caution of course that when the exam happens NO ACTION is to be taken at that time) so many Dr.s look and RIP in the same motion without consulting you, informing you or your son what's going to happen or providing any pain relief... this must be avoided. Most adhesions seperate on their own, but if there is a situation where they are causing him pain (like if there is concentrated pulling during erections- or if there is debris being trapped in that tunnel behind the corona- or if that caused infections- it's possible that you'd want to get the adhesions lysed (with pain relief) to help out with that, also sometimes a simple steroid ointment will help them release. You might want to check out an article by VanHowe about the variability of penile appearance in the CIRP library... it discusses how it's normal and not such a big deal for kids to have some adhesions for several yerars and that most adhesions are "self resolving"... my problem with the idea of "self resolving" is like a Dr. saying that trees that fall in the woods are silent- just because a Dr. doesn't do it- doesn't mean that the penis adhesion fairy showed up in the middle of the night and fixed it with pixie dust... maybe the kid had three years of painful erections and finally they tore painfully- that doesn't mean that the "leave it alone" approach by a Dr. was any less invasive that "let him suffer with it in the privacy of his own room and he'll take care of it." approach. I'm all for being very conservative- wait and see is fine unless there is a problem. Without knowing the age of your son, I'm not sure what you would say to him to explain the configuration.