This clinical study will evaluate the efficacy and safety of microfocused ultrasound treatment in patients with facial pigmentary diseases and rosacea.

The study includes two independent disease cohorts: a facial pigmentary disease cohort and a rosacea cohort. Participants in each cohort will be randomly assigned to receive either active microfocused ultrasound treatment or sham stimulation. Sham stimulation will follow the same treatment procedure as active treatment but will not deliver effective therapeutic ultrasound energy.

Participants will receive one treatment session per month for 6 months and will be followed for up to 12 months. The study will assess changes in clinical severity scores, digital skin imaging parameters, patient-reported symptoms, quality of life, and safety outcomes, including adverse events.

This is a prospective, randomized, sham-controlled, assessor-blinded, parallel-group clinical study designed to evaluate the efficacy and safety of microfocused ultrasound in patients with facial pigmentary diseases and rosacea.

The study consists of two independent disease cohorts. The facial pigmentary disease cohort will include participants with eligible facial pigmentary disorders, such as melasma, periorbital hyperpigmentation, melanosis, and lichen planus pigmentosus. The rosacea cohort will include participants who meet the diagnostic criteria for rosacea. Each cohort will be randomized separately in a 1:1 ratio to either the active microfocused ultrasound group or the sham stimulation control group.

Participants assigned to the active treatment group will receive microfocused ultrasound treatment once monthly for 6 months. The planned treatment parameters include a power range of 3.76 to 5.12 W and a frequency of 8 Hz, with each session stopped after the preset treatment endpoint is reached. Participants assigned to the sham stimulation group will undergo the same procedure, including use of ultrasound coupling gel, probe contact, treatment environment, and treatment duration, but without delivery of effective therapeutic energy.

Efficacy assessments will include investigator-assessed clinical severity scores, patient-reported outcome measures, VISIA digital skin analysis, dermatology-related quality of life assessment, and psychological symptom assessment. Safety will be evaluated through physical examination, vital signs, and monitoring of adverse events and serious adverse events throughout the study.

An exploratory tissue sample substudy may be conducted in participants who voluntarily provide additional informed consent. This substudy is exploratory and will not affect participation in the main study or the primary efficacy analysis.

Inclusion Criteria:

1. Male or female participants aged 20 to 60 years.
2. Diagnosed by the investigator as having facial pigmentary disease or rosacea eligible for this study.
3. Participants with rosacea must meet the diagnostic criteria of the Chinese Guideline for the Diagnosis and Treatment of Rosacea (2021 edition).
4. Participants with facial pigmentary diseases must be diagnosed by two dermatologists with associate senior professional title or above, based on clinical manifestations and, when necessary, auxiliary examinations such as Wood's lamp examination, dermoscopy, or skin histopathology. Eligible pigmentary diseases may include melasma, periorbital hyperpigmentation, melanosis, lichen planus pigmentosus, or other facial pigmentary diseases considered suitable for this study.
5. The skin lesions are suitable for microfocused ultrasound treatment and follow-up assessment.
6. Able to comply with study treatment, follow-up visits, photography, and related assessments during the study.
7. Able to understand the study procedures, voluntarily participate in the study, and sign written informed consent.

Exclusion Criteria:

1. Pregnant or lactating women, or women planning to become pregnant during the study period.
2. Known allergy to ultrasound coupling gel or any of its excipients.
3. Presence of other obvious active inflammatory skin diseases, infectious skin diseases, or other facial skin conditions that may affect efficacy evaluation, apart from the target disease of this study.
4. Use within 1 month before screening of topical medications or procedures that may affect study evaluation, including but not limited to corticosteroids, calcineurin inhibitors, depigmenting agents, or energy-based treatments.
5. Severe cardiac, hepatic, renal, or other important organ dysfunction, or other severe systemic diseases that, in the investigator's judgment, may affect the safety or efficacy evaluation of this study.
6. Participation in another clinical trial within 30 days before screening.
7. History of prolonged intense sun exposure within 1 month before screening, or expected inability to avoid significant sun exposure or outdoor exposure during the study period, which may affect study evaluation.
8. Any other condition that, in the investigator's judgment, makes the participant unsuitable for this study.

Individual participant data will not be publicly shared due to participant privacy protection, the sensitive nature of facial images and clinical dermatology data, and institutional data management requirements. De-identified aggregate results may be reported in scientific publications.

Participants and outcome assessors will be masked to treatment assignment. Sham stimulation will use the same treatment procedure as active microfocused ultrasound, including ultrasound coupling gel, probe contact, treatment environment, and treatment duration, but without delivery of effective therapeutic energy. Treatment operators cannot be masked because they perform either active or sham treatment, but they will not participate in efficacy assessment, image evaluation, or statistical analysis. Treatment assignments will be maintained through a central randomization system until unmasking according to the study protocol.