Hemangioma is the most common type of vascular malformation, also known as birthmark. It is a benign tumor that originates from residual embryonic angiogenic cells. Hemangiomas are most common in infants at birth or shortly after birth. 60% to 70% of hemangiomas may subside by the age of 8 years, but some hemangiomas may continue to increase in size and spread rapidly, resulting in changes in appearance and dysfunction, causing psychological disorders and inconvenience to patients’ daily lives. Are hemangiomas common? Hemangiomas are the most common benign tumors in infants, with an incidence of about 4-10%. They are usually more common in girls, about 3-5 times more common than in boys. They are more common in the white race than in the yellow race and are rare in the black race. The incidence of preterm low birth weight (weighing less than 1 kg at birth) is as high as 25%, while the incidence of twins is also higher. What causes hemangiomas? Although there is a family history of hemangiomas in 10% of infants, it is not a genetic disease. There are no known foods or medications that can cause hemangiomas, and there is no association with maternal behavior during pregnancy. Current research suggests that there may be a link to a genetic mutation that occurs during the transformation of progenitor cells to endothelial cells within the fetus. When do hemangiomas appear? Hemangiomas are detected at birth in about 1/3 of affected children. Usually, the average time for hemangiomas to appear is when the infant is two weeks old, while deep hemangiomas may not be detected until 3 to 4 months of age. Adults rarely develop hemangiomas. Where do hemangiomas occur? About 60% of hemangiomas occur in the head and neck, about 25% in the trunk, and about 15% in the extremities. The vast majority (about 80%) of hemangiomas occur in a single site, and a few can occur in multiple sites. Although most hemangiomas occur on the surface of the body, a small percentage can occur in the liver, gastrointestinal tract, and even inside the brain. What does a hemangioma look like? The appearance of a hemangioma depends on a number of factors, including whether it grows on the surface of the body or deeper, whether it is proliferating, stable, or receding, and whether it is discovered at birth or after birth. Hemangiomas that are on the surface of the skin are called superficial hemangiomas, and they are usually bright red in color, similar to strawberry, which is why they used to be called “strawberry hemangiomas”. At the same time, subcutaneous veins can be seen radiating along the tumor. As the hemangioma fades, the color of the hemangioma will gradually become lighter, and usually by the age of 7, the color of the hemangioma will have completely faded. Hemangiomas underneath the skin are called deep hemangiomas and appear as a bruise or light blue color, and in some cases are not visible at all. This type of hemangioma is usually discovered when the baby is 2-4 months old.