This is a multi-center, randomized, double-blind, vehicle-controlled, and sequential group Phase 2 study. Eligible subjects aged 18 to 75 years old with PWB will receive Hemoporfin PDT or vehicle PDT in 8-week cycles at fixed drug dose (5 mg/kg) and different light fluence.

This is a multi-center, randomized, double-blind, vehicle-controlled, and sequential group Phase 2 study. Eligible subjects aged 18 to 75 years old with PWB will receive Hemoporfin PDT or vehicle PDT in cycles at fixed drug dose (5 mg/kg) and different light fluences. This study will be conducted in two sequential stages, each contains the same schedule, which includes Screening Period, Treatment Period apart; subsequent treatment is based on efficacy evaluation, and End of Study.

Inclusion Criteria:

1. Subject must be 18 to 75 years of age inclusive, at the time of signing the informed consent.

2. Subject is Fitzpatrick skin type I-VI.

3. A male subject must agree to use contraception during the Treatment Period and for at least 6 months after the last dose of study treatment and refrain from donating sperm during this period.

4. A female subject is eligible to participate if she is not pregnant, not breastfeeding, and at least one of the following conditions applies:

   Not a woman of childbearing potential (WOCBP) . OR A WOCBP who agrees to follow the contraceptive guidance during the Treatment Period and for at least 30 days after the last dose of study treatment.

5. The subject has a clinical diagnosis of PWB located i) on the extremities, trunk, caudal cervical and/or retroauricular area (Stage One); ii) on the face and/or neck (Stage Two).

6. The longest diameter of the treatment area is ≥3 cm, and the short diameter is ≥2 cm.

7. Subject is capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.

8. Subject, in the Investigator's opinion, is in good general health and free of any disease state or physical condition that may impair the evaluation of PWB or expose the subject to an unacceptable risk by study participation.

9. If the subject has a history of epilepsy or seizure, the disease must remain stable for at least 6 months prior to C1D1.

Exclusion Criteria:

1. Subject is pregnant, lactating, or is planning to become pregnant during the study.
2. Subject has plaque/nodular changes and severe hypertrophy within the target PWB area.
3. Subject has Sturge-Weber syndrome.
4. Subject has any skin pathology or condition that, in the Investigator's opinion, could interfere with the evaluation of the study drug or requires use of interfering topical, systemic, or surgical therapy.
5. The subject has evidence of scarring within the target PWB area and/or the subject has a history of hypertrophic scarring or keloidal scarring.
6. Subject is immunosuppressed related to medication use and/or disease.
7. The subject has clinical abnormalities, as determined by the Investigator, which makes them unsuitable for receiving study treatment in the Investigator's opinion at Screening.
8. Subject has received any therapy on the treatment region that, in the Investigator's opinion, may affect the target PWB area.
9. Subject is known or in the opinion of the Investigator likely to be noncompliant with the requirements of the study protocol (eg, due to alcoholism, drug dependency, mental incapacity).
10. Subject has a history of either significant neurological events (such as major stroke) or a mental condition rendering him/her unable to understand the nature, scope, and possible consequences of the study.
11. Subject has an unstable cardiac disease or has any medical condition that in the opinion of the Investigator may worsen from receipt of study treatment or subject participation.
12. The subject has a history of cutaneous photosensitization, porphyria, or photodermatosis.
13. The subject has the need or has plans to be exposed to artificial tanning devices or excessive sunlight during the study.