Hemangiomas are benign lesions caused by the overgrowth of endothelial cells (the cells lining blood vessels). They are often small at birth and then grow rapidly during a period of "proliferation" which typically lasts 2 years. Most then move inward and shrink in size by the age of 10, leaving some thin extra skin at the site.
Treatment must be coordinated carefully because these are benign growths that generally shrink in size over time. If complete surgical removal is possible, it will often provide the child with a reprieve from teasing during the school years. Hemangiomas which bleed and ulcerate may need to be treated more urgently and often respond to medication.
Many other types of vascular malformations exist, many of which do not shrink over time. The nature of your child's vascular malformation must be decided before a treatment plan can be prepared. This may require a combination of radiology, pediatric dermatology, and surgery.