Ultraviolet B Phototherapy Worsened Psoriasis Vulgaris

Abstract

Psoriasis vulgaris is a chronic, complex, immune-mediated inflammatory disease with a genetic predisposition and a global prevalence of 2%–4%. One treatment option for psoriasis is narrowband ultraviolet B (NBUVB) phototherapy. Phototherapy can reduce cytokines and chemical mediators that trigger psoriasis. However, there is a clinical subset of photosensitive psoriasis in 5.5%–24% of cases, wherein NBUVB exposure at sub-minimal doses can worsen psoriasis lesions. Herein, we present a case of a 23-year-old man with a seven-year history of psoriasis and who completed eight sessions of the secukinumab injection protocol with full re-mission. The patient complained of worsening psoriasis lesions, and his psoriasis area and severity index score increased to 6.5. He was scheduled to undergo two sessions of whole-body NBUVB phototherapy at 500 mJ/cm2 for, which then further worsened the lesions, progressing into erythrodermic psoriasis. Phototherapy was withheld, and the patient was hospitalized. In 5.5%–24% of psoriasis cases, UV light exposure can worsen psoriasis. This condition is related to the genetic predisposition of HLA-Cw*0602 and CARD14 mutation at locus 2 (PSORS2), which causes a different immune response when the skin is exposed to UV light, including phototherapy. In these cases, there is no physiological suppression of propsoriatic cytokines and mediators. Instead, propsoriatic mediators are increased through various pathways, including tumor necrosis factor-alpha, interferon gamma, interleukin (IL)-1, IL-6, or IL-17, after UV exposure. Thus, understanding photosensi-tive psoriasis is essential, and further studies are needed to determine the best course of treatment in these patients.