Hi - Hank has given you some great advice, as he has personal experience. My grandson also has a facial port wine stain. His lower lip has hypertrophy, as well as the gums. Like Hank pointed out, it is difficult to determine if any one person will be affected by hypertrophy. Most parents I have talked to, say their doctors now treat the lip and gums early on (if affected) while they treat the rest of the sklin with the port wine stain. They have been seeing good results. When my grandson started laser treatment 11 years ago, they only treated his face, not the gums and lips, and he does have hypertrophy of both areas - However, this is not a postitive indicator of what may happen with another patient. There are many factors that can impact treatment and results (location, depth, etc.).
How old is your son, how large is the pws area and what color is it? What has your doctor advised?
I know at first, all the information and stories you hear can really be overwhelming at times. It can be frightening, but don't let it consume you. We are here for you and your son. If you need anything else, please let me know.