A hemangioma is an abnormal build up of blood vessels in the skin or internal organs. Hemangiomas are one of the most common birthmarks in newborns. Most hemangiomas are not present at birth but develop within the first few weeks to months of life. They are found in up to 10 percent of babies by the age of one. Most children with hemangiomas have only one. Many have a few. Rarely, children may have many, both on the skin and in the internal organs. Some have enough extra vascular tissue to cause anemia or platelet problems. Hemangiomas, both deep and superficial, undergo a rapid growth phase in which the volume and size increase rapidly.

This phase is followed by a rest phase, in which the hemangioma changes very little, and an involutional phase in which the hemangioma begins to disappear. During the involutional phase, hemangiomas may disappear completely. Large cavernous hemangiomas distort the skin around them and will ultimately leave visible changes in the skin. A superficial capillary hemangioma may involutes completely, leaving no evidence of its past presence. There are two types of liver hemangioma: cavernous and hemangioendothelioma. Cavernous hemangioma arises in individuals of all ages and all over the world. Cavernous hemangiomata are more common in women than men. Estrogens may augment their size.

Cavernous hemangiomata can vary in size and be as large as several centimeters. The margins of the tumors are usually well-defined. Hemangiomata are filled with vascular channels of various sizes and also contain fibrous tissue. Thrombi (clotted blood) may be present in the vascular channels. Hemangioendotheliomata are generally seen only in children. Hemangiomas are the most common benign tumor in infants. Between 4% and 10% of Caucasian infants have at least one hemangioma. Hemangiomas are three to five times more familiar in females (mainly fair-skinned girls) than in males, and arise more frequently in Caucasian infants than in Asian infants.

They are rare in African-American infants. The incidence of hemangiomas may be as high as 25% in premature children of a low birth weight (fewer than 1,000 grams). They are also more common in twins. Most cavernous hepatic hemangiomas are treated only if there is persistent pain. The mainstay of treatment is oral corticosteroid therapy. Smaller raised lesions are sometimes treated with injection of corticosteroid directly into the lesion. Pulsed dye laser can be helpful for very early flat external lesions if they seem in cosmetically significant areas or for those lesions that leave residual surface blood vessels in the case of incomplete resolution.