||A nevus flammeus is present at birth and is characterized by irregularly outlined dull red or bluish-red patches which are not elevated above the level of the surrounding skin. There are two types of nevus flammeus: The medially located nevus flammeus occurs most commonly in the occipital region and in the center of the face. This type of nevus is not associated with other congenital abnormalities, whereas the laterally located nevus flammeus is usually unilateral in location and occurs most commonly on one side of the face or on an extremity. The laterally located nevus flammeus is frequently associated with malformations of other blood vessels, as for example in the SturgeWeber syndrome.
In both types of nevus flammeus no histologic abnormalities are visible in early life, and in later life dilatation and ectasis of the capillaries in the deeper layers of the dermis and subcutaneous tissue occurs.
Since no histologic abnormalities are present early in life, it is believed that the nevus flammeus represents a congenital weakness of the capillary walls, that is, a telangiectasia and not a true angioma.
In this patient with Sturge-Weber syndrome, a large nevus flammeus involves the left side of the patient's face.