A hemangioma is a bright red birthmark that shows up at birth or in the first or second week of life. It looks like a rubbery bump and is made up of extra blood vessels in the skin.
A hemangioma can occur anywhere on the body, but most commonly appears on the face, scalp, chest or back. Treatment for a baby's hemangioma (infantile hemangioma) usually isn't needed as it fades over time. A child who has this condition during infancy usually has little visible trace of the growth by age 10. You may want to consider treatment if a hemangioma interferes with seeing, breathing or other functions.
Cited from the Mayo Clinic & the American Academy of Dermatology