Current knowledge of the pathogenesis of infantile hemangiomas.

Infantile hemangiomas are the most common benign tumor of infancy, occurring shortly after birth in 5% to 10% of white infants. Hemangiomas occur in infants of all races but are most common in those who are white. These lesions are preponderant in females compared with males at rates of 3:1 to 5:1. Many hemangiomas are discrete, well-circumscribed masses present in the head and neck. Some hemangiomas are segmental and diffuse, often involving large areas of the extremities or the head and neck. Chorionic villus sampling at 9 to 12 weeks of gestation has been associated with a 21% increased incidence of hemangiomas in infants. Most hemangiomas occur sporadically without a hereditary component. However, in a few families, hemangiomas segregate as a highly penetrant, autosomal dominant trait. Gene linkage studies of familial infantile hemangiomas show evidence of linkage to chromosome 5q31-33.