Brief Answer:Arteriovenous malformation
Thanks for your question and the photograph.
Is this an venous malformation. If so it sounds although an attempt was made at sclerotherpy to block the enlarged veins.
The 1st thing to say is that if this lesion is not enlarging or causing any functional problems then it can be left alone.
Sometimes medical treatment can be of benefit to reduce the side of certain arteriovenous malformations, one drug that is sometimes used is a beta blocker
fails then the only other option is surgical removal.
I hope this answers your question.