What causes birthmarks to form?
Birthmarks that are red (as opposed to brown) contain vascular tissue ("hemangiomas") left over from the time of fetal development. You could think of hemangiomas as leftover ingredients. They are red because they contain the hemoglobin pigment, which contains iron. Congenital hemangiomas usually resolve on their own in childhood and do not usually require treatment. Port wine stains, on the other hand, persist into adulthood and may be treated using the laser.
How do lasers help treat hemangiomas?
Each laser produces light energy on one specific wavelength. Each application requires a specific wavelength and there is no "all seasons" laser, which is why there are so many different lasers used in medicine. You may have heard of lasers that target melanin to remove unwanted hair. When treating vascular lesions, the laser targets hemoglobin. It is important for patients to understand which laser is most appropriate for their needs.
Lasers used to treat hemangiomas deliver their energy in a single wavelength that is well-absorbed by hemoglobin. The laser that is specific for this purpose is the "pulsed dye" laser and produces energy at a wavelength (585 – 600 nm) that is close to a peak in the absorption spectrum for oxy-hemoglobin. On a microscopic scale, the red blood cells absorb the energy, heating up the lining of the tiny blood vessels (capillaries) which causes them to collapse so they are no longer visible. Because of the laser's specificity ("selective photothermolysis"), the surrounding tissues are not injured. The hemoglobin that is released into the tissues by the burst red cells and damaged capillaries accounts for the bruising. The byproducts of this destruction are mopped up by the body and afterward the damaged blood vessels are replaced with normal capillaries.
How do lasers help treat facial spider veins?
The "pulsed dye" laser is also used to treat acquired vascular lesions, such as facial spider veins ("telangiectasia") and redness of the neck ("poikiloderma"). Many patients with a ruddy complexion are told they have rosacea and are treated with Metrogel®, a topical antibiotic. These patients are often good candidates for laser treatment and find it more effective and rewarding.
Alternative non-laser light-based systems use a flashlamp ( like the flash on a camera) and then use a filter to select a range of wavelengths. These systems are called "intense pulsed light," or IPL. The "photo-facial" is a popular example. IPL systems are not optimal for targeting hemoglobin because the energy is not all delivered on the most effective wavelength. Accordingly, these non-laser systems tend to be less effective for vascular lesions and need to be administered as a course of treatments. They will incrementally reduce red and brown skin discoloration but they are less suitable treatments for spider veins and port wine stains.
Laser treatment and Bruising
Bruising ("purpura") does occur and these purple spots take up to ten days to resolve. Scarring is unlikely when typical energy settings are used.
Not all of the veins are eliminated in one treatment. Some are permanently eliminated and others persist. New ones are likely to appear in time. Patients should count on returning from time to time for additional treatments. This way, they can be kept under control.
If there is a particularly stubborn hemangioma, I am likely to increase the energy setting at a retreatment. I tell patients that there may in fact be a small scar at this site. Usually if there is a scar, it is inconspicuous and certainly less noticeable than the hemangioma. The alternative is surgical excision which would leave a small scar anyway.
Patients with port wine stains present a more difficult problem because of the density of vascular tissue. Each treatment will provide an incremental lightening, but elimination is unlikely. The advantage of treatment with the pulsed dye laser is that scarring or pigment change, which can occur with older nonselective treatments, is avoided.