RESUMO
In the first issue of Actas Dermo-Sifiliográficas, Juan de Azúa published a magnificent article on contact dermatitis caused by hair dyes, which reflects his profound knowledge of allergy and how the skin responds to chemical stimuli. It gives a brilliant description of irritative and allergic dermatitis, although without naming the allergic form explicitly. Of note is how he is concerned about the composition of <