RESUMEN
BACKGROUND: Chronic actinic dermatitis (CAD) is a rare disease worldwide. It has been defined on the basis of three criteria: 1) clinical - a persistent eczematous eruption on sun- exposed area with possible extension into non-exposed areas, 2) photobiological - a reduction in the minimal erythema dose to UVB irradiation, and possibly longer wavelengths, and 3) histologic - an appearance consistent with chronic eczema, with or without the presence of lymphoma-like changes. However, only a few clinicohistopathologic and photobiological analyses of CAD have been undertaken in Korea. OBJECTIVE: To explore photoallergens and/or allergens causing or thought to be associated with CAD in Korean patients, and to compare the photopatch or patch test results in Korea with those from other countries. METHODS: Thirty-five Korean patients with CAD were enrolled for this study. Photopatch tests were carried out by applying two sets of the Scandinavian photopatch series to each patient. Two days after application, the photopatch tests were analysed, and one set of the photoallergens was irradiated with 50% of the MED-UVA. Both sets of photoallergens were examined 2 days later. A European standard series was used to assess the patch tests. At two and four days after application, patch tests were analysed. RESULT: Twenty-seven of the 35 patients (77.1%) who had photopatch tests showed positive responses; balsam of Peru, promethazine HCl, perfume mix, fentichlor, chlorhexidine digluconate, and chlorpromazine HCl were the common photoallergens that elicited a positive response. Twenty-one of the 35 patients (70%) showed allergy to nickel, chrome, and/or ammoniated mercury. Noticeably, photoallergens such as balsam of Peru, perfume mix, cobalt, and captan revealed positive reactions in the patch tests, too. CONCLUSION: In 77.1% and 74.3% of CAD patients, photoallergens and allergens were identified, respectively. Among them, 57.1% showed positive reactions including both photopatch and patch tests. After the most frequent photoallergens, perfume and spices, and phenothiazines or related antihistamines ranked next and were found to be a unique characteristic to Korea. Photopatch and patchtests are the method for detecting photoallergens and allergens as important initiating agents and are the diagnostic tool for the epidemiologic study of CAD.