Occupational pigmented contact dermatitis from Naphthol AS

Hyper-pigmentation as a manifestation of contact sensitivity to optical brighteners has previously been reported. In 1973 we observed an epidemic of pigmented contact dermatitis occurring in a textile mill in connection with the manufacture of drill fabrics impregnated with a recently introduced azo dye coupling component Naphthol AS. Of the 53 workers included in the study, 12 presented a spotted pattern of hyperpigmentation mainly affecting the exposed areas, but without pruritus, 18 were pigmented to a lesser degree, and in 21 it was not possible to discern any well-defined discoloration; some of the patients in the last group, however, complained of slight pruritus. The last two patients who were fair-skinned showed a reddish-brown pigmentation and a well pronounced pruritus. Hyper-pigmentation was most pronounced in individuals with dark complexions, whereas fair-skinned patient also showed "classical" eczematous symptoms including pruritus. A field study demonstrated direct exposure to the chemical. All 53 patients were patch-tested with Naphthol AS 5% in water, and 24 were found to be positive. Histological features were melanocyte proliferation, incontinence of pigment, and various degrees of damage to the basal layer.