Histological Characteristics of Port-Wine Stains with Complete Regression After Photodynamic Therapy Treatment: A 7-Year Follow-Up.

Vascular-targeted photodynamic therapy (PDT) is an effective alternative treatment choice for port-wine stains (PWSs). The histological characteristics of PWSs after PDT treatment have not yet been reported. To investigate the morphological features of PWSs treated by PDT and define the histopathological characteristics of PWS that achieve clinical cure. Thirteen patients with facial PWSs, who presented with complete regressive PWS lesions after a mean of 4.38 (standard deviation = 4.907) sessions of PDT. Post-treatment biopsy samples were obtained from each patient. The number of blood vessels, vascular diameter, and depth were measured and compared in all samples of PDT-regressive sites, PDT-resistant sites, and normal skin. Within the 7-year follow-up after PDT, there was no recurrence in the regression area of PDT. In the PDT-regressive sites, within 800 μm of the dermal-epidermal junction, the dilated vessels were occluded and remained fissure-like after PDT. When the vascular lesions within 800 μm of the dermal-epidermal junction were closed after PDT, a stable clinical cure (no recurrence) was achieved.