A cooling technique intended to protect the skin may actually increase the risk of discoloration in dark-skinned patients undergoing laser treatments for mole-like skin lesions, according to a report in the September issue of Archives of Dermatology.
Hyperpigmentation, when the skin's cells increase their production of the brown or black pigment melanin, is the most common adverse effect of laser treatments in dark-skinned individuals, according to background information in the article. “It is not life-threatening, but postinflammatory hyperpigmentation may cause substantial psychological problems,” the authors write. “The treatment of postinflammatory hyperpigmentation is difficult and time-consuming, often lasting many months to achieve the desired results, which causes frustration in patients and physicians.” Some clinicians have hypothesized that skin cooling, which decreases pain and allows the use of higher laser frequencies, could also reduce hyperpigmentation after laser treatment.
Woraphong Manuskiatti, M.D., and colleagues at Mahidol University, Bangkok, Thailand, used laser irradiation (from a 1,064-nanometer Q-switched Nd:YAG laser) to treat 23 Thai women (average age 43) with Hori nevus, blue-brown pigmented spots on the skin that develop later in life. “One randomly selected face side of each patient was cooled using a cold air cooling device during and 30 seconds before and after laser irradiation, and the other side was irradiated without cooling,” the authors write. Two dermatologists not involved in treatment examined digital photographs to measure the occurrence of hyperpigmentation before treatment and one, two, three, four and 12 weeks after treatment.