Polymorphic Light Eruption

Abstract

This chapter discusses the prevalence, etiology, prognosis and diagnostic tests of polymorphic light eruption (PLE). A commonly postulated mechanism is that PLE might be an autoimmune disorder in which there is an abnormal delayed hypersensitivity to an endogenous molecule rendered antigenic by UV exposure. Treatments can be divided into prophylactic or suppressive. The aim of prophylactic phototherapy is to increase the duration of sunlight exposure required to elicit PLE, and so as to improve the quality of life for those severely affected patients who cannot carry out normal activities because very limited sunlight exposure triggers the eruption. Suppressive treatment should alleviate symptoms (particularly itch), and speed the resolution of PLE when it occurs. A randomized, patient-masked, controlled trial including 25 adults found that narrowband (TL-01) ultraviolet B (UVB) was as effective as psoralen-ultraviolet A (PUVA) in preventing episodes of PLE following a treatment course.