Hemangiomas are benign [violaceous, reddish] tumors of the vascular endothelium. Hemangiomas of infancy are the most common type of hemangiomas, characterized by a unique natural history of growth in early infancy, followed by slow involution over the next several years. Hemangiomas may be present at the time of birth as so-called precursor lesions in approximately half of the cases. Rarely are they fully-formed tumors at birth.

Unfortunately it is not possible to predict which hemangiomas will involute quickly or which will develop complications. Therefore, it is important to have each child evaluated by a physician specializing in hemangiomas. Many of the Children's Hospitals have Vascular Birthmark programs consisting of multispecialty clinics experienced in the management and treatment of hemangiomas.

Typically the hemangioma appears within 2 weeks after birth. Only 2% are actually visible at birth. It is usually noticed as a small red blemish or bump, most parents interpret it as a bruise or scratch but quickly become alarmed as it begins to rapidly grow. Current research indicates two growth cycles: 0-4 months for the first cycle, with a pause from 4-6 months and then a second growth, from 6 months - 1 year or sometimes longer.