Abstract: Objective To study the precipitating factors, clinical features, photobiological test features and therapy in patients with chronic actinic dermatitis. Methods Clinical data of 86 cases with chronic actinic dermatitis were analyzed retrospectively. Results The male:female ratio was 11.29:1. The average age of onset was 57.1 years. Of the 86 patients, 20.9% were found to have definite precipitating factors and 78.9% with a light exacerbating history. The first on set often took place in spring. The seasonal predominance gradually disappeared along with prolongation of clinical course of the disease. Lesions were distributed primarily or most severely on the exposed skin and consisted of erythema, papules, exudation, crusting, sometimes thickened papules(45.5%)and plaques(37.3%). A lowered ultraviolet-B minimal erythema dose (MED) was found in 77.9%of patients, ranging from 4 mJ/cm² to 20 mJ/cm². A lowered ultraviolet-A MED was found in 95.3% of patients, ranging from 0.2 J/cm² to 15 J/cm². Photoallergens were confirmed in 14 patients by photopatch test. Therapy with ultraviolet light and photoallergens avoidance, broadspectrum sunscreens, topical or systemic cort icosteroids was effective in most cases. Spontaneous remission was found in some patients after repeated relapses. Conclusions Diagnosis of chronic actinic derm atitis depends mainly on the clinical features and results of photobiological tests. Appropriate ultraviolet light and photoallergen avoidance are important in the therapy.

Key words: Dermatitis, photoallergic