High intensity focused ultrasound as a potential new modality for the treatment of pigmentary skin disorder.

Abstract

The clinical skin tightening benefits of high intensity focused ultrasound (HIFU) have been established, but its mechanism of action in pigmented skin disorders remains unknown. We macroscopically and histopathologically investigated dermatological changes after HIFU at different exposure doses in a UVB-induced guinea pig model of hyperpigmentation. We applied HIFU irradiation at 0.1 and 0.2J/cm(2) to UVB-induced spotty hyperpigmentation in guinea pig skin. The therapeutic effects of HIFU were judged based on gross appearance using photography, dermoscopy, and chromametry during a period of 3weeks after HIFU irradiation. Histological assessments were performed using Fontana-Masson staining 1day before and 3weeks after HIFU irradiation. Macroscopically, UVB-induced hyperpigmentation was significantly reduced 2weeks after HIFU with 0.2J/cm(2) , and 3weeks after HIFU with 0.1J/cm(2) . Histopathologically, the heavy deposition of melanin in the epidermis induced by UVB exposure was reduced 3weeks after HIFU irradiation. We confirmed that HIFU has a positive effect on UVB-induced hyperpigmentation as well as mechanical destructive activity. We suggest that HIFU may be useful as an alternative modality for human patients suffering from skin pigmentary conditions.