Plaque-based sub-blistering dosimetry: Reaching PASI-75 after two treatments with 308-nm excimer laser in a generalized psoriasis patient.

Background: Generalized UVB phototherapy has been established as an effective and safe treatment for chronic plaque-type psoriasis for decades and in recent years, targeted 308-nm excimer laser has emerged as an equally safe and more effective treatment option. While traditional dosimetry for laser has been determined either through minimal erythema dose (MED) or a combination of the patient's Fitzpatrick skin type and the level of plaque induration, we have developed "Plaque-based Sub-blistering Dosimtery" based on observations that administering anywhere from 8 to 16 multiples of MED to psoriatic plaques has resulted in clearance after one treatment with longer remission rates than the traditional dosing protocol. Case report: The authors describe a case in which a patient achieved PASI 75 following only two treatments with 308nm excimer laser using this new protocol. Biopsies taken before and after treatment reveal a dramatic decrease in CD4 + T cells as well as TNF-alpha- and IL-2-producing T cells. Conclusion: This case demonstrates using a more aggressive dosing protocol determined by plaque testing is well-tolerated and can lead to excellent clearance with minimal side effects and comorbidity.