Treatment of nevus of Ota by Q-switched ruby laser

Background: There are few reports on therapy for nevus of Ota. Moreover, traditional treatments are largely palliative or risk permanent pigmentary changes and/or scarring. Objective: The efficacy of the Q-switched ruby laser (694 nm, 40 nsec) as a therapy for nevus of Ota was investigated. Methods: Nine nevi or portions thereof were irradiated up to six times with 4.5 and/or 7.5 J/cm² at a mean exposure interval of 3 weeks. Sequential skin biopsy specimens were processed for light microscopy, immunohistochemistry, and electron microscopy. Results: Cosmetic improvement occurred at both doses in the irradiated parts of the six nevi available for follow-up. No appreciable difference was noted between single and multiple treatments. There was no gross scarring. Light microscopy revealed dose-related immediate injury with more melanophages and fewer dermal melanocytes after irradiation in comparison with control areas. Electron microscopic distinction between dermal melanocytes and melanin-laden macrophages was difficult. A monoclonal antibody to human melanosome-specific antigen type 1 (HMSA-1) was used to distinguish between the two cell populations. Conclusion: Our findings suggest that the Q-switched ruby laser is useful for treating nevus of Ota.