Background/purpose: Chronic actinic dermatitis (CAD) is a spectrum of diseases with chronic photosensitivity occurring mostly among middle-aged and older men. We seek to explore the characteristics and pathogenesis of CAD among the Chinese population.
Methods: The medical records of 488 CAD cases diagnosed by phototesting at Huashan Hospital, Fudan University from January 2014 to December 2018 were analyzed retrospectively.
Results: Among the 488 patients, 344 were male and 144 were female. 84.8% of the cases were over 40 years old at the age of onset, while the remaining with an early age of onset had a prevalence of atopic history of 21.6%. Up to 45.0% of the patients reported excessive sun exposure and outdoor activities before the initiation of symptoms. The typical skin lesions were erythema, papules and plaques laid predominantly in sun-exposed areas. 42.8% of the cases showed sensitivity to UVB only, 20.7% were both sensitive to UVA and UVB, and 18.2% had UVA sensitivity only. The most predominant photoallergens were chlorpromazine (80.1%), thimerosal (17.2%), potassium dichromate (12.7%), etc. The most prevalent patch test allergens were potassium dichromate (24.4%), thimerosal (20.5%), formaldehyde (16.8%), etc. CONCLUSIONS: CAD was more commonly seen in males over 40 years old. The action spectrum of Chinese patients is primarily in the UVB range. Exposure to excessive sunlight or contact allergens and photoallergens are important risk factors. Photobiology tests are essential in detecting photosensitivity and recognizing potential photosensitizers. Early avoidance of confirmed photoallergens and sun exposure may prevent photosensitive reactions from progressing into persistent photosensitivity.
Keywords: chronic actinic dermatitis; patch tests; photosensitivity disorders; retrospective studies.
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