A Port Wine Stain (PWS), also known as nevus flammeus, is a congenital birthmark appearing as a flat patch of skin, typically pink, red, or purplish. It is caused by an abnormality in the small blood vessels near the skin’s surface. PWS are permanent vascular malformations that do not fade or disappear on their own.
Understanding Why Port Wine Stains Are Permanent
Port Wine Stains are classified as capillary malformations, meaning they are structural abnormalities in the blood vessels present from birth. The stain is caused by the permanent dilation of small blood vessels, specifically capillaries and post-capillary venules, located in the dermis layer of the skin.
These vessels remain widened because they lack the proper nerve fibers necessary to regulate their diameter, a process known as vascular tone. Normal blood vessels can constrict, but the deficiency or absence of these nerve elements prevents the PWS vessels from shrinking naturally. Researchers have also identified a somatic mutation in the GNAQ gene as an underlying cause, which contributes to the progressive dilation of these vessels.
How Port Wine Stains Change Over a Lifetime
If left untreated, the PWS appearance progresses and changes as the person ages. While they begin as flat, pink, or light red patches in infancy, the vessels continue to slowly widen due to progressive vascular ectasia. This causes the stain to darken, often shifting to a deep red, purple, or violaceous hue.
The long-term changes also involve the skin texture within the birthmark. The lesion often begins to thicken, a process called hypertrophy, commonly starting in early adulthood, with the median age of onset around 31 years. By the fifth decade of life, many untreated PWS patients experience this thickening and nodularity. Small, raised bumps or nodules may also develop within the stain, increasing the risk of spontaneous bleeding from minor trauma.
The Primary Medical Treatment for PWS
The primary treatment for Port Wine Stains is Pulsed Dye Laser (PDL) therapy, which works through selective photothermolysis. This targeted treatment uses a concentrated beam of light, typically at 595 nanometers, which is absorbed by the hemoglobin within the dilated red blood cells. The light energy converts to heat, selectively destroying the abnormal vessels without significant damage to the surrounding skin tissue.
PDL therapy is most effective when started early, often in infancy, because smaller, shallower vessels respond better. Treatment remains effective at any age, although older, thicker lesions may require more intensive sessions. Patients typically require multiple treatments spaced several weeks apart for optimal lightening. While the goal is significant color reduction and prevention of future thickening, complete clearance is often difficult to achieve.
When a Port Wine Stain Signals Other Health Concerns
Although most PWS are isolated skin conditions, the location can signal an underlying neurological or ocular syndrome. A PWS located on the face, particularly involving the forehead and upper eyelid area, which corresponds to the ophthalmic division of the trigeminal nerve, may be associated with Sturge-Weber Syndrome (SWS). This rare disorder involves vascular malformations in the brain and eyes on the same side as the facial PWS.
Infants with a PWS in this specific facial area have an increased risk for SWS and require specialized screening. Associated symptoms of SWS include neurological problems, such as seizures beginning within the first year of life, and eye conditions like glaucoma (increased pressure within the eye). Prompt follow-up with an ophthalmologist and neurologist is necessary to monitor and manage these potential systemic complications.