Laser resurfacing-induced hypopigmentation: histologic alterations and repigmentation with topical photochemotherapy.

BACKGROUND Hypopigmentation is a relatively common side effect of CO2 laser resurfacing. Little is known regarding the histologic features of the areas of pigmentation loss. To date, hypopigmentation is considered a permanent complication of this procedure. OBJECTIVE To assess the histologic features of hypopigmentation caused by laser resurfacing and to evaluate the efficacy and safety of topical psoralen photochemotherapy. METHODS Ten patients were included in this pilot study. Four had baseline biopsies performed. Histologic parameters assessed included epidermal melanin, dermal melanophages, perivascular inflammation, Mel-5 immunostaining for melanocytes, and dermal fibrosis. Seven patients were treated twice a week with topical photochemotherapy utilizing 0.001% 8-methoxypsoralen. RESULTS All of the biopsy specimens demonstrated varying quantities of epidermal melanin and residual epidermal melanocytes. Mild perivascular inflammation was evident in two specimens. Superficial dermal fibrosis was noted in all biopsy specimens. Topical photochemotherapy induced moderate to excellent repigmentation in 71% of the treated patients. Adverse effects were minimal. CONCLUSION The results of this investigation suggest that hypopigmentation induced by laser resurfacing may result from a suppression of melanogenesis rather than destruction of area melanocytes. The preliminary data further suggest that hypopigmentation caused by laser resurfacing can be effectively treated by topical photochemotherapy.