Treatment of Ota's nevus by Q-switched alexandrite laser: therapeutic outcome in relation to clinical and histopathological findings

Ota's nevus is a dermal melanocytic disease which causes serious cosmetic p roblems for affected individuals. Recently Q-switched lasers with a pulse d uration of 100 nsec or less became available for patient treatment. We eval uated the clinical efficacy of the Q-switched alexandrite laser (755 nm, 10 0 nsec) in relation to the histopathological findings. Fifty-five Korean pa tients with Ota's nevus were treated with a Q-switched alexandrite laser fo r three sessions (7.5 J/cm(2)) at three month intervals. Skin biopsies were taken in all of the patients before treatment and immediately after treatm ent in five patients. Clinical effectiveness and side effects were evaluate d by direct observation and photographs. Pigment clearing was excellent in 27 patients (49%), good in 17 patients (31%), fair in 7 patients (13%) and poor in 4 (7%) patients. Postinflammatory hyperpigmentation developed in 30 patients (55%) which resolved within four months. But there were no seriou s complications including scarring or textural change. The therapeutic outc ome was not affected by color but by depth of the nevus. Nevi of Ota with d epth of 1 mm or less were associated with excellent or good results. Q-switched alexandrite laser is a very effective and safe tool for treating Ota's nevus. Depth of 1 mm or less of dermal melanocytes was a good progno stic marker.