Definition: 'Photo-patch Test'
photo-patch testType: Term
1. a test of contact photosensitization: after application of a patch with the suspected sensitizer for 48 hours to two sites, if there is no reaction, one area is exposed to a weak erythema dose of sunlight or ultraviolet light; if positive, a more severe reaction with vesiculation develops at the exposed patch area than the nonexposed skin patch site.
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