Contact dermatitis to a labile henna skin tattoo

Background. Contact dermatitis to henna are rarely reported. Most of the lime, they are related to additives, especially scented oils or paraphenylene diamine. This latter substance is added to shorten the time of application and to enhance the darkness of the color. We report one case of an allergic contact dermatitis to henna skin tattoo, probably related to a paraphenylene diamine derivative. Case report. A 25-year-old woman developed an allergic contact dermatitis at the site of application of two henna skin tattoos on her right arm. She never dyed her hair and wore dark clothing without problems. Epicutaneous tests were positive for henna paste, paraphenylene diamine, N-isopropyl-N'phenyiparaphenylene diamine and five chemical dyes, probably related to cross-reactions between paraphenylene diamine and these dyes. Epicutaneous test with henna powder was negative, confirming the absence of allergy to henna. Fluorescence analysis detected the presence of a primary amine in henna paste but high performance liquid chromatography analysis did not reveal the presence of paraphenylene diamine or any suspect dye. An another allergen, related compound of paraphenylene diamine, was probably present but we failed to identify it with precision. Discussion. Labile henna skin tattoos are in fashion at the moment in western European countries. They can be a secrete source of paraphenylene diamine, or one of its related compounds, sensitization.