Safety and efficacy of high-intensity macro-focused ultrasound for solar lentigo in Chinese patients: a prospective study.

Background: Solar lentigo (SL) is a skin disorder associated with photoaging. Studies suggest that high-intensity focused ultrasound can improve UV-induced hyperpigmentation and melasma.

Objectives: To evaluate the efficacy and safety of high-intensity macro-focused ultrasound (HI-MFU) for treating SL in Chinese.

Methods: This is a prospective, single-center study. Twenty-one patients with SL on both cheeks underwent HI-MFU treatment. Follow-ups at baseline and 2, 4, 6, and 8 weeks post-treatment were conducted to assess improvements using clinical imaging, noninvasive skin assessments, and the Global Esthetic Improvement Scale.

Results: The lesional and non-lesional areas showed an increase in L* values at all time points (p < 0.05). Transepidermal water loss values decreased on the left at 8 weeks (p < 0.001). Only two patients experienced transient mild pain and localized edema post-treatment. Two-photon microscopy revealed an uneven two-photon-excited fluorescence signal enhancement surrounding the nuclei of the stratum granulosum and stratum spinosum cells in the SL. At 8 weeks post-treatment, fluorescence signals in both areas were reduced compared to those at baseline.

Conclusions: HI-MFU effectively and safely treats SL and enhances skin tightness, lightness, and barrier function, suggesting its ultrasound-toning potential.