Infrared radiation increases skin damage induced by other wavelengths in solar urticaria.
BACKGROUND
Photodermatoses are typically investigated by analyzing the individual or combined effects of ultraviolet A (UVA), ultraviolet B (UVB), and visible light using light sources that simulate portions of the solar spectrum. Infrared radiation (IRR), however, accounts for 53% of incident solar radiation, but its effects are not taken into account in standard phototest protocols.


OBJECTIVE
The aim was to analyze the effects of IRR, alone and combined with UVA and visible light on solar urticaria lesions, with a distinction between infrared A (IRA) and infrared B (IRB).


METHODS
We performed standard phototests with UVA and visible light in four patients with solar urticaria and also tested the effects after blocking IRB with a water filter. To analyze the direct effect of IRR, we performed phototests with IRA and IRB.


RESULTS
Initial standard phototests that were all positive found the induction of erythema and whealing, while when IRR was blocked from the UVA and visible light sources, three of the patients developed no lesions, while the fourth developed a very small wheal.


CONCLUSIONS
These results suggest that IRR has the potential to produce and exacerbate lesions caused by other types of radiation. Consideration of these effects during phototesting could help prevent diagnostic errors.
Photobiological Dermatology Laboratory, Medical Research Center, Department of Dermatology and Medicine, Faculty of Medicine, University of Málaga, Málaga, Spain.
María Victoria
MV
de Gálvez
Photobiological Dermatology Laboratory, Medical Research Center, Department of Dermatology and Medicine, Faculty of Medicine, University of Málaga, Málaga, Spain.
José
J
Aguilera
Photobiological Dermatology Laboratory, Medical Research Center, Department of Dermatology and Medicine, Faculty of Medicine, University of Málaga, Málaga, Spain.
Cristina
C
Sánchez-Roldán
Photobiological Dermatology Laboratory, Medical Research Center, Department of Dermatology and Medicine, Faculty of Medicine, University of Málaga, Málaga, Spain.|Dermatology Service, Hospital Clínico Universitario Virgen de la Victoria, Málaga, Spain.
Enrique
E
Herrera-Ceballos
D005260:Female; D006801:Humans; D007259:Infrared Rays / Q000009:adverse effects*; D008297:Male; D010787:Photosensitivity Disorders / Q000378:metabolism* / Q000473:pathology; D012867:Skin / Q000378:metabolism* / Q000473:pathology; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014581:Urticaria / Q000378:metabolism* / Q000473:pathology
infrared radiation; photodermatosis; photodiagnosis; phototest; solar urticaria