your doctor may be right in asking you to weight till your son gets 15 years of age or older.
as this disease needs to be treated immediately only if its rapidly progressive, causing compression of eye balls, or hearing loss
ar any other difficulty in the child.
generally this aggressive form is rarely encountered and in most of the cases it is very slowly progressive and of benign nature. this generally grows in the growing years of the child under effect of growth hormones.
so even if you get it resected at this stage it may recur again and your son may require a repeat resection. so let it grow to its final size when it's growth stops and then you can get it done.
meanwhile, you should be under regular followup under your doctor to watch for any change in the nature of the swelling and to undertake any corrective steps if needed.
hope i was able to answer your query satisfactorily