Benign birthmark. An infantile hemangioma, or "strawberry mark, " is a very common type of birthmark made of blood vessels. Most hemangiomas are not visible at birth. They may at first only appear as a small bruise, scratch or a tiny red bump. Unlike other types of birthmarks, hemangiomas grow and change greatly during the first months of life. They may occur anywhere on the skin surface but are most common on hnt.
Variable. Variable, sizes. Usually a mm. Or so in adults is common and no great concern. In children, very superficial ones may atrophy even if greater circumference.