Lentigo maligna occurring in a patient with the past history of laser therapy

A 70-year-old Japanese woman visited our clinic with a pigmented patch on her face from her upper lip to under her nose following laser therapy 15 years ago. Physical examination revealed an asymmetrical dark brown macule with a clear border along with irregular black dots measuring 20 mm. A biopsy specimen showed some irregular-sized atypical melanocytes with deep-colored nuclei on staining. There were observed on the basal layer and a few of them in the prickle-cell layer only in the epidermis. We diagnosed this case as lentigo maligna (LM). Total resection and reconstruction with the Abbe flap were carried out. We searched previous literature for reports on laser therapies resulting in LM and determined the following: (1) there were no reports indicating that laser therapy is one of the causes of LM, (2) judging from invalidity of treatment or recurrence of the condition, laser therapies were considered ineffective for LM treatment, and (3) the numbers of patients undergoing laser therapies, who were not diagnosed with LM, were increasing.