A benign (not cancer) blood vessel tumor that forms on the skin, in the tissue below the skin, or in an organ. Infantile hemangiomas may be raised or flat and usually appear as bright red-blue lesions on the skin. They may sometimes be called a “strawberry mark”. They can occur anywhere on or in the body, but usually form on the skin of the head and neck. Infantile hemangiomas are not usually seen at birth but appear when the infant is 3 to 6 weeks old. They usually get bigger, then stop growing and slowly go away on their own. Infantile hemangiomas are the most common type of vascular tumor in children.