๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
EPIDEMIOLOGY
IHs arise during the first year of life and are the most common tumor of infancy. They develop in 4%โ5% of infants, with lesions usually noted within the first several weeks of life. IHs may occur more commonly in White infants than in other racial groups. A femaleโ:โmale ratio of 2โ5โ:โ1 has been noted in multiple retrospective studies as well as prospective studies conducted in dermatology practices; however, a hospital-based prospective birth-cohort study found no female predominance among infants who developed an IH. A higher femaleโ:โmale ratio of 7โ9โ:โ1 has been reported for patients with severe, complicated IHs.
IHs also develop more frequently in premature infants. Low birth weight represents an independent IH risk factor, and IHs affect 25%โ30% of infants with a birth weight <1000โg and 15% of those with a birth weight between 1000 and 1500โg4. Factors associated with placental insufficiency (e.g. preeclampsia, placenta previa) are also associated with IH development, while prematurity and multiple gestation pregnancies are linked with the development of multifocal IHs. One study found a threefold increased incidence in infants born following chorionic villus sampling compared to those born following amniocentesis or without a history of prenatal instrumentation. A higher maternal age has also been associated with hemangioma development.
IHs typically arise sporadically, although a family history has been reported in up to a third of patients. The frequent occurrence of hemangiomas in the general population makes it difficult to assess the true familial incidence, and no specific genes have been consistently implicated.