It is a technique designed to protect the skin, however, skin cooling after laser treatments for mole-like skin lesion could actually raise the risk of discoloration for people with dark skin, says a report in Archives of Dermatology (JAMA/Archives), September issue.
Hyperpigmentation is the most frequent adverse effect of laser treatments in dark skinned people, the authors explain. Hyperpigmentation is when the cells of the skin boost their production of the brown or black pigment melanin. “It is not life-threatening, but post inflammatory hyperpigmentation may cause substantial psychological problems. The treatment of post inflammatory hyperpigmentation is difficult and time-consuming, often lasting many months to achieve the desired results, which causes frustration in patients and physicians,” the authors write.
Some doctors have put forward the idea that skin cooling, which lowers pain and lets the doctor use higher laser frequencies, might also reduce hyperpigmentation after laser treatment.
Woraphong Manuskiatti, M.D.,Mahidol University, Bangkok, Thailand, and team used laser irradiation to treat 23 Thai women, average age 43, with Hori nervus – they used a 1,064-nanometer Q-switched Nd:YAG laser. Hori nervus are blue brown pigmented spots on the skin which tend to appear later on in life. Of the 23 women, 21 completed the study.
The authors explain “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.”
Two dermatologists looked at digital photographs to detect/measure the occurrence of hyperpigmentation before treatment and 1, 2, 3, 4 and 12 weeks after treatment. These two dermatologists had not been involved in any part of the treatment.
62% (13) of the participants developed hyperpigmentation on the cooled side of the face, while 24% (5) developed hyperpigmentation on the uncooled side. One woman developed it on both sides while two developed no hyperpigmentation at all.
All but one of the hyperpigmentation cases resolved themselves within 12 weeks of the treatment. In 62% of cases the hyperpigmentation appeared two weeks after treatment.
The authors wrote “No difference in clinical improvement was observed regarding the cooling used on one side during treatment.”
They concluded “Future studies should address the question of whether the other methods of epidermal cooling are associated with an increased risk of post inflammatory hyperpigmentation.”
“Effect of Cold Air Cooling on the Incidence of Post inflammatory Hyperpigmentation After Q-Switched Nd:YAG Laser Treatment of Acquired Bilateral Nevus of Ota-like Macules”
Woraphong Manuskiatti, MD; Sasima Eimpunth, MD; Rungsima Wanitphakdeedecha, MD
Arch Dermatol. 2007;143:1139-1143.
Written by: Christian Nordqvist