Previous therapies for port wine stains usually cause unacceptable scarring or obtain poor effect. Because port wine is a congenital vasculopathy consisting of an abnormal network of capillaries in the upper dermis with an overlying normal epidermis and the researchers found the tumor blood vessels were occluded accompanying the necrosis of the tumor after PDT. The author and his colleagues started a series of animal and clinical studies since 1991 about photodynamic therapy for port wine stain an they established the method of PDT for PWS. The clinical studies of over 1500 cases proved that PWS can be cured by PDT without scar formation because there is no thermal effect involved. No relapse was found within a maximum follow-up of six years.
"Photodynamic therapy for port wine stains", Proc. SPIE 3344, 1997 Shanghai International Conference on Laser Medicine and Surgery, (2 November 1998); doi: 10.1117/12.330125; https://doi.org/10.1117/12.330125