Long-lasting Allergic Patch Test Reaction / 대한피부과학회지

A long-lasting allergic patch test reaction (LLAPTR) is generally defined as a positive patch test reaction that persists for weeks or months, at least 2 weeks after application of the allergen. Several allergens, including gold sodium thiosulfate, have been reported as causes of LLAPTR, however, it has never been described in the Korean dermatologic literature. We report a case of LLAPTR to Cl+Me-Isothiazolinone (Kathon CG) and p-tert-butylphenol formaldehyde resin (PTBP-FR) in a 45-year-old woman with suspected allergic contact dermatitis.