AT WCD 2015
VANCOUVER, B.C. (FRONTLINE MEDICAL NEWS) – Laser treatment can markedly improve the appearance of lentigines and nevi of Ota, although response is variable for most other benign pigmented lesions of the epidermis and dermis, Dr. Jason Rivers said at the World Congress of Dermatology.
“The best approach is to choose the device based on the location of pigment within the skin,” said Dr. Rivers, a dermatologist with Pacific Dermaesthetics in Vancouver. “Melanin has a fairly wide absorption spectrum, from the 400s down into the infrared spectrum. As we go further down into the infrared spectrum, we need to use higher fluencies, because we need to penetrate deeper into the skin.”
Q-switched 532-nm Nd:YAG laser is a good choice for facial lentigines, according to Dr. Rivers. “You can see marked improvement after one treatment, but you can be quite effective with various modalities,” he said. Intense pulsed light (IPL) therapy also can be effective for lentigines, including for patients with darker skin, although there is a risk of postinflammatory hyperpigmentation, he cautioned. Another option is 1,927 nm fractionated thulium fiber laser, he said. “Mopping up a lot of things at one time can be extremely effective, especially for lentigines on the face.”
For patients seeking removal of freckles, intense pulse light can clear a wide area of dyschromia in one session, Dr. Rivers continued. For mucosal melanosis, Q-switched lasers such as 532-nm frequency-doubled Nd:YAG, 694-nm ruby, or 755-nm alexandrite can be effective and are associated with minimal or no scarring, he added.
Café au lait patches typically respond well to combined treatment with 532-nm and 1,064-nm lasers, according to Dr. Rivers. A total of 10 treatment sessions spaced over 2-3 years has given him a durable response and without skin changes as a result of laser treatment, he said. However, some data indicate that café au lait patches might respond even better to Q-switched 755-nm alexandrite laser instead of conventional Q-switched lasers, he noted.
Becker’s nevus presents a much greater challenge. “Studies have looked at many kinds of lasers, and in all cases results may be suboptimal,” Dr. Rivers said. “For one of my patients with Becker’s nevus, I’ve basically thrown the kitchen sink at her, and we’re pretty much back to square one.” Q-switched 755-nm alexandrite laser can provide substantial clearing after 3 treatments in 4 weeks, but results might not be durable, he added. Laser therapy of nevus spilus also is “hit or miss,” although some studies suggest that Q-switched ruby laser is more effective than alexandrite for these lesions, he added.
Among the benign pigmented lesions of the dermis, nevus of Ota usually responds best to laser treatment, particularly with Q-switched 694-nm ruby or Q-switched 1,064-nm Nd:YAG, Dr. Rivers said. Data indicate that children younger than 10 years might have more superficially placed pigment cells that can be treated with lower fluence, such as 2.2 instead of 2.8 J, he noted.
Both congenital and acquired melanocytic nevi respond variably to laser therapy, Dr. Rivers said. For acquired lesions, options include Q-switched 532-nm, fully ablative carbon dioxide resurfacing, and continuous wave laser, he said. Long-pulsed alexandrite laser therapy can partiallyly clear congenital lesions after just one treatment session, and patients can then be given the option of fully ablative carbon dioxide resurfacing, he said.
Dermatologic laser therapy can, of course, cause adverse effects. The best treatment for laser-induced chrysiasis is prevention, but lesions can clear with Q-switched 1,064-nm laser treatment, Dr. Rivers said. Pigmentation might occur at the lesion margin, but fades with time, he noted.
Melanoma also has been reported as a consequence of dermatologic laser therapy. While sublethal laser damage can increase DNA damage in vitro, Q-switched ruby laser does not seem to induce genetic changes, Dr. Rivers said. In addition, some lesions were probably melanoma to begin with, he said, noting that failure to diagnose malignant melanoma is among the most common allegations in medical liability claims against dermatologists.
Dr. Rivers disclosed no relevant conflicts of interest.