An infantile hemangioma is a kind of vascular tumor made up of blood vessels, commonly referred to as a “strawberry birthmark.” The vascular tumor can be superficial (growing on the skin surface), appearing as a bright red, bumpy, lesion. It can also be deep (growing under the skin), presenting as a bluish lump. These vascular birthmarks appear shortly after birth and then undergo a period of growth (known as the proliferative phase) typically lasting a few months. This is followed by a period of shrinkage (known as the involution phase), which is much slower and can take years. While many hemangiomas completely resolve, some will leave behind residual skin changes or scars. Infantile hemangiomas are fairly common, and are most often seen in girls, premature infants, white infants, and multiple births (twins, triplets).