Contact dermatitis from black henna tattoo in child due to paraphenylenediamine.

Temporary henna tattoos have become increasingly popular, particularly among children and teenagers. The word "henna" is of Persian origin, and it is prepared from the plant Lawsonia inermis belonging to the family Lythraceae. Concerning allergic reactions, natural henna paste is rarely responsible for contact dermatitis, which is more frequent if paraphenylenediamine (PPD) is added to the paste. The authors present a case of female child with erythematous exanthems that appeared after the application of black henna tattoo. A diagnosis of contact dermatitis to black henna tattoo was hypothesised. Epicutaneous tests were performed at the Immunoalergology Department of the Coimbra University Hospital using standard European battery and natural henna paste. The tests revealed positive reaction to PPD.