Factors affecting response, number of laser sessions and complications in nevus of Ota treated by Q-switched alexandrite laser: a retrospective study.

Abstract The aim of this study was to study and analyze the factors influencing the treatment response to Q-switched alexandrite laser in patients with nevus of Ota and the factors influencing the number of laser sessions. Forty-eight patients treated with Q-switched alexandrite between 2009 and 2013 for nevus of Ota were enrolled in this retrospective, single-center study. The subjects (13 male, 35 female) were divided into three groups according to the number of treatment sessions. Patients were then called back to the hospital for a follow-up interview and examination. Single and multiple variate analyses of various factors were performed. The 48 patients were predominantly female (35 female, 13 male, F:M ratio = 2.7:1), mean age 17.2±10.41. Twenty-five (52.1%) had lesion on the right side of the face, 22 (45.8%) on the left side, and one (2.1%) on both sides. The predominant color was brown (41.7%), followed by cyan (39.6%) and lividity (18.8%). Satisfactory result was observed in all patients, after 3 to 11 treatment sessions (mean 5.37±2); 19 of these (39.6%) needed three to four sessions (short treatment sessions), 22 (45.8%) needed five to seven sessions (intermediate treatment sessions), and 7 (14.6%) needed nine to eleven sessions (long treatment sessions). The clinical response and treatment sessions of the young-age group were significantly better than the adult group. Those with higher Tanino's classification needed more treatment sessions. Dark-colored lesions, which reflect deep melanosis of the lesion, needed more sessions than lighter-colored lesions. As for skin color, better response was obtained in light-skinned patients than in dark-skinned ones. Two patients showed transient hypopigmentation that lasted for less than six months, and recurrence has been seen in one child with dark-colored lesion. Q-switched alexandrite laser is an ideal minimally-invasive method for treating nevus of Ota. Fewer treatment sessions are needed for children and younger patients, whereas brown lesion, lower Tanino's classification and light skin patients.