Re:23 yr old female Vascular Malformation or Hemangioma?
Hemangiomas are supposed to appear in the infancy. When a vascular birthmark appears later in life, it is rather a vascular malformation, either venous or arteriovenous. I have an arteriovenous malformation of the lip. It appeared when I was 38 yrs old and at the time it was diagnosed as a H. It grew very slowly and steadily until I had no choice but to have it surgically excised 20 years later -- that is in 2003. Some vascular malformations grow fast, others slowly. Most doctors will recommend the "leave-it-alone" solution because treatments seldom bring good results and the tumor recurs.
But the word "hemangioma" is also used as a kind of generic word (like the word "tumor"). Even at the Vascular Anomalies Clinic of Little Rock I was admitted, says the record, for an "excision of lip hemangioma".
Anyway, you should get the opinion of a doctor who knows about VM (see the link "Find a Physician" on this site): the vast majority of doctors are quite ignorant on the subject.
I hope this can help you a little, but you need an expert consultation, don't stop your inquiring and searching.
Take good care of you.