Photo-Patch Tests - the Results in Photosensitive Patients

Overview

The epidemiology of contact photoallergy in our population is not well known at present.Therefore the basic aim of our project was to establish the scale of diagnostic methods in theassessment of skin photosensitivity state by use of photo-patch tests. We tested some substances(TROLAB® set provided by Hermal comp.). These substances could cause photoallergy, phototoxicity,and/or contact sensitivity. In the beginning of the studywe have assessed the minimal erythema doseand its individual seasonal variations to determine the time required for photo-patch testing. Themean suberythematous UV-A dose of 5 J/cm2 was used.The group of 27 patients was studied: 17 patients with known photosensitivity in personal historyand 10 persons without photosensitivity as controls. Although in 5 controls (50 %) contact hypersensitivitywas detected, contact allergy was found out also in 8 cases (47 %) of photosensitive group.Photoallergic reaction appeared on the skin of 2 healthy controls. The incidence of positive photoallergicresponders within the photosensitive group was 5 persons (29.4 %). The results of studyconducted with sunscreens showed that propandione, cinnamates and oxybenzone were the mostfrequent photoallergenic substances. These data suggest that some photosensitive troubles could becaused by a skin response against photoactivated sunscreen components. Thus the physical (nonphotoallergenic)forms of sunscreens are recommended in essentially sensitive people, especiallywhen used from childhood.

Key words:
photo-patch test - contact photoallergy - sunscreens