Lasers That Target Melanin
Lasers should not be used as a substitute for surgical removal of lentigo maligna, Dr. Spencer said.
In 11 patients with lentigo maligna who were treated with the Q-switched ruby laser on four occasions in a 6-month period, 6 of 13 biopsies taken after treatment were still positive for the lesion. Studies of lentigo maligna treatments with 532-nm and 1,064-nm Q-switched Nd:YAG lasers have shown similar results.
Some people may want to undergo laser removal of common acquired nevi for cosmetic reasons. There is a variable response to such treatment, in which nevi partially or completely lighten in color. This "debulks" and superficially removes the nevus from the epidermis but leaves residual nevus cells in the dermis, he said.
It is unclear if laser treatment of dysplastic or congenital, especially giant, nevi reduces the risk of melanoma. Treatment of atypical-appearing melanocytic lesions with lasers can provide an excellent cosmetic result, but it may run the risk of promoting malignant transformation. Lasers strip a lesion of its outer layer of UV-protecting melanin and create a scar in the papillary dermis that may clinically mask a deeper component, Dr. Spencer said.
"These concerns are very real," he said, but "people have been cautiously trying lasers on nevi for 20 years, and we haven't seen any malignant transformation."
Dr. Spencer said that laser removal of nevi "should be studied in a more formal way, but people have been very afraid to do this."
Clinicians have widely accepted the removal of nevi of Ota with lasers for only cosmetic improvement, so laser removal of large congenital and common acquired nevi should be considered, he said.
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