Hypopigmentation occurred after Er:YAG laser resurfacing

초록

Background: Hypopigmentation is one of the complications developed after laser resurfacing. There have been few data about hypopigmentation developed after Er:YAG laser resurfacing, especially in darker skin. Objective: The objective of this study was to assess the clinical and histopathologic features of hypopigmentation developed after Er:YAG laser resurfacing. Methods: One hundred and ninety patients have been included in this study. Ninety seven patients were treated with short pulsed Er:YAG laser, 2mm spot sized handpiece at the setting of 12.5-15.0 J/cm2. Fifty two patients were treated with variable pulsed Er:YAG laser, 5 mm spot sized handpiece at the setting of 7.0-7.5 J/cm2 and 7 msec pulse duration. Forty one patients were treated with dual mode Er:YAG laser, 4 mm spot sized scanner at the setting of 17.5 J/cm2 ablation mode and 3.15 J/cm2 coagulation mode. Incidence, time of onset, duration of hypopigmentation were evaluated throughout the medical charts and serially checked photographs. Skin biopsy was performed in four patients at the hypopigmentation site for histopathologic and electron microscopic examinations with informed consents. Results: Hypopigmentation was observed in twenty six patients; eight in short pulsed Er:YAG laser, eight in variable pulsed Er:YAG laser, ten in dual mode Er:YAG laser. According to the time of onset of hypopigmentation, twelve patients developed hypopigmentation within one month, five patients in two months, three patients within three months, three patients within four months, two patients within five months, and one patient within six months. Twenty out of twenty six patients recovered skin coloration within six months, and two patients within twelve months. On the other hand, four patients had persisted hypopigmentation for more than one year. Melanosome appeared to be decreased but melanocytes appeared to be present in normal numbers on the histopathologic and electron microscopic examinations. Conclusion: Although hypopigmentation is one of the frequent complicaions of Er:YAG laser resurfacing, it is temporary in most cases. Thermal damage due to long pulse duration of laser seems to be a very important factor in inducing hypopigmentation.

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