Objective: To investigate the effect of Q-switched alexandrite laser irradiation on dermal melanocytes of nevus of Ota.
Methods: Multiple biopsies were carried out on 4 patients with nevus of Ota before and after laser irradiation. Altogether 11 samples were examined under light microscope and 14 under transmission electron microscope.
Results: Immediately after laser irradiation, the dermal melanocytes were destroyed, the melanosomes were degenerated with central vesicle formation within most of them, and intradermal round vacuoles appeared. The epidermis remained intact. Three months to 1 year after irradiation, the degenerated melanosomes and cell debris were scavenged mainly by macrophages. Dermal melanocytes gradually decreased. No fibrosis was found.
Conclusion: Q-switched alexandrite laser can selectively destroy dermal melanocytes of nevus of Ota and treat the disease safely.