Persistent erythema after hemoporfin-mediated photodynamic therapy for port-wine stains and its management with intense pulsed light: a case series of three patients.

OBJECTIVE: Hemoporfin-mediated photodynamic therapy (HMME-PDT) is an alternative treatment for port-wine stain (PWS) birthmarks; however, persistent erythema extending beyond the expected recovery period may occur in a small number of patients. This study aimed to describe the clinical features of persistent erythema following HMME-PDT and document the changes and adverse events after intense pulsed light (IPL) treatment. METHODS: Three patients with PWS who developed erythema persisting for more than 4 weeks after HMME-PDT and subsequently received IPL treatment were analyzed retrospectively. All patients received 3-5 IPL sessions (wavelength: 590/640 nm, fluence: 8-12 J/cm², pulse duration: 30-40 ms) and treatment intervals of 3-4 weeks. Clinical characteristics, erythema duration, accompanying symptoms, changes in erythematous area and redness intensity, and adverse events were recorded. RESULTS: After IPL treatment, the erythematous area decreased approximately 30%, 9%, and 12%, respectively. Redness intensity also showed a decreasing trend. One patient developed crusting and local thickening after HMME-PDT, while no other notable adverse reactions beyond persistent erythema were documented. No new pigmentary abnormalities, scarring, or other serious adverse events were observed. CONCLUSION: Persistent erythema may persist beyond the expected recovery period after HMME-PDT, with improvement observed after IPL intervention in all three patients. However, the specific contribution of IPL remains uncertain, and further studies are needed to clarify the natural course and optimal management of this condition.