Immunologically Mediated Photodermatoses

Abstract

Electromagnetic radiation may cause distinct skin conditions. The immunologically mediated photodermatoses (IMP, previous term: idiopathic photodermatoses) represent a heterogenous group of disorders presenting with pathologic skin reactions caused by optical radiation, particularly in the UVA wavelength region. The exact pathomechanism in IMP remains to be elucidated; however, it is very likely (auto)-immunologic in nature. Polymorphic light eruption, actinic prurigo, hydroa vacciniforme, chronic actinic dermatitis, and solar urticaria are the most important conditions that may be summarized under the term IMP. IMP frequently result in a significant reduction in quality of life in affected individuals, mainly because of troublesome symptoms such as intractable itch and pain. Photodiagnostic procedures are mandatory for the exact determination of action spectra and the degree of photosensitivity. Broad-spectrum photoprotection is essential in the prevention of IMP. Photo(chemo)therapeutic regimens are predominantly used to increase the cutaneous immunologic tolerance against ambient UV radiation. In severe forms of IMP, immunomodulatory and immunosuppressive therapies may need to be considered. Overall, IMP form a significant group of skin conditions that can be extremely disabling to the patient and are difficult to diagnose and treat.

Ultraviolet A1 Phototherapy for Fibrosing Conditions

“…They concluded that sunscreens must block sufficiently UV-A1 wavelengths as well (74). Furthermore, UV-A1 can induce photodermatoses or reactivate herpes flares (16, 75). A recent case study reported a 37-years-old female with a persistent polymorphous light eruption lasting for 5 weeks following UV-A1 phototherapy (76).…”

Chronic Actinic Dermatitis/Actinic Reticuloid

“…1,4,5,13,[15][16][17][18][19][20] In this study, we describe our experience with 37 patients with CAD/AR. It was described as a severe photodermatitis, which clinically and pathologically can mimic CTCL.…”

“…1 The term CAD combines conditions reported as persistent light reaction, photosensitive eczema, photosensitivity dermatitis, and AR. 4,5 Women are less commonly affected compromising only 10%-22% of the affected population. [1][2][3] However, generalized erythroderma with the involvement of the entire skin can ensue in severe cases.…”

Photoprotection and abnormal cutaneous photosensitivity

“…Polymorphous light eruption is the most common idiopathic photodermatosis with a prevalence of 10-20% among women in Western European countries and in the USA [2]. The pathogenesis is most likely related to a type IV reaction to an unknown photo-activated skin antigen.…”

“…They are classified into five general subgroups: idiopathic; secondary to exogenous agents; secondary to endogenous agents; photoexacerbated inflammatory dermatoses; and photosensitive genodermatoses (Box 1) [1][2][3][4][5].…”