Contact dermatitis to a labile henna skin tattoo

Background. Contact dermatitis to henna are rarely reported. Most of the li me, 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 allergi c contact dermatitis to henna skin tattoo, probably related to a paraphenyl ene diamine derivative. Case report. A 25-year-old woman developed an allergic contact dermatitis a t the site of application of two henna skin tattoos on her right arm. She n ever dyed her hair and wore dark clothing without problems. Epicutaneous te sts were positive for henna paste, paraphenylene diamine, N-isopropyl-N'phe nyiparaphenylene diamine and five chemical dyes, probably related to cross- reactions between paraphenylene diamine and these dyes. Epicutaneous test w ith henna powder was negative, confirming the absence of allergy to henna. Fluorescence analysis detected the presence of a primary amine in henna pas te but high performance liquid chromatography analysis did not reveal the p resence of paraphenylene diamine or any suspect dye. An another allergen, r elated compound of paraphenylene diamine, was probably present but we faile d to identify it with precision. Discussion. Labile henna skin tattoos are in fashion at the moment in weste rn European countries. They can be a secrete source of paraphenylene diamin e, or one of its related compounds, sensitization.