H., do you have room in your boat for one more mom? LOL! My daughter has one of those on her arm. She's had it for about a year now. Maybe a little longer. What I was told was:
They are not contageous.
They are harmless.
They will just fall off on their own without scaring.
They may be around for a while.
My girlfriend's little boy had quite a few & had his for a couple years but they did just come off on their own & as far as I can see, there is no scar.
She has 2 other kids and neither of those kids, herself or her husband ever got them. They did not spread on her son either.
So, I am kinda hoping my daughter's is the same way but so far we're following that path. Good luck!