he is 4.5. when born we noticed a bulge at back of his head, which after a bit of medical messing about ( Oooh we've never seen this before it will need emergency surgery said one- just what two freaked out new parents needed to hear)it was diagnosed as basically just a big gap in the bone. it is covered by skin and hair and is about the size of a thumb. DS hasn't even noticed it and it hasn't posed any problems except that i worry about the lack of brain protection. surgeon told us it would probably grow over but has changed his mind now and wants to insert a steel plate under the skin to cover it. Has this happened to anyone else? how do i explain it to him? am waking every night in cold sweat having nightmares about operations.