The Significance of Photopatch Testing and Photoallergic Contact Dermatitis: 10-years experience - นัยสำคัญของ Photopatch Test และโรค Photoallergic Contact Dermatitis - ประสบการณ์ 10 ปี

Abstract

Photopatch testing (PPT) is a standard tool to help making and confirming diagnosis of photoallergic
contact dermatitis (PACD) that should correlate to patients’ history and clinical manifestation. This retrospective
study reports the significance of PPT and PACD, conducted for 10 years between 2000 and 2009
at the Institute of Dermatology. Among 270 patients who completed PPT, 72 patients (26.67%) had PPT
positive, but only 14/72 (19.4%) had relevant to the patients’ history and skin lesions which could make
definite diagnosis as PACD. Among them, oxybenzone, a sunscreen substance was the most common causative
agent (35.7%) which was corresponded with other reports, followed by promethazine hydrochloride,
chlorpromazine hydrochloride, fragrance mix, triclocarban and fenticlor. Oxybenzone also caused allergic
reaction in 6 cases. Data from this study would be useful for providing information relevant to the improvement
of the use of PPT in the diagnosis and management of PACD and other related skin diseases, as well as
the future use of data for the development of commercial products that are less harmful to the people.
Key words: photoallergic contact dermatitis, photopatch test, sunscreen, oxybenzone