Photodynamic therapy and CO fractional laser combination therapy for verruca vulgaris caused by Koebner phenomenon - Two case reports.

Verruca vulgaris, caused by the human papillomavirus (HPV), can profoundly impact an individual's quality of life and necessitate therapeutic intervention. The challenges associated with treating verruca vulgaris are particularly noteworthy when they manifest as the Koebner phenomenon (KP). In this report, we present two cases of verruca vulgaris that developed KP following cryotherapy. Some studies have suggested that pretreatment with laser therapy enhances the efficacy of Photodynamic Therapy (PDT). Given the inefficacy of cryotherapy and the emergence of KP in our patients, we opted for a treatment approach that combined PDT with CO fractional laser (COFL), resulting in complete resolution without any notable adverse effects or recurrence during the follow-up period. Our cases underscore the importance of considering KP when verruca vulgaris exhibit enlargement and proliferation post-cryotherapy. Furthermore, this combined treatment modality demonstrates its effectiveness and safety. Additionally, our experience highlights the need for a large-scale study to determine the optimal photosensitizer concentration for the treatment of thick, enlarged verruca vulgaris.