TREATMENT OF NEVUS OF OTA BY Q-SWITCHED RUBY-LASER

Background: There are few reports on therapy for nevus of Ota. Moreove r, traditional treatments are largely palliative or risk permanent pig mentary changes and/or scarring. Objective: The efficacy of the Q-swit ched ruby laser (694 nm, 40 nsec) as a therapy for nevus of Ota was in vestigated. Methods: Nine nevi or portions thereof were irradiated up to six times with 4.5 and/or 7.5 J/cm(2) at a mean exposure interval o f 3 weeks. Sequential skin biopsy specimens were processed for light m icroscopy, immunohistochemistry, and electron microscopy. Results: Cos metic improvement occurred at both doses in the irradiated parts of th e six nevi available for follow-up. No appreciable difference was note d between single and multiple treatments. There was no gross scarring. Light microscopy revealed dose-related immediate injury with more mel anophages and fewer dermal melanocytes after irradiation in comparison with control areas. Electron microscopic distinction between dermal m elanocytes and melanin-laden macrophages was difficult. A monoclonal a ntibody to human melanosome specific antigen type 1 (HMSA-1) was used to distinguish between the two cell populations. Conclusion: Our findi ngs suggest that the Q-switched ruby laser is useful for treating nevu s of Ota.