Pigmented cosmetic dermatitis and coal tar dyes.

Patch tests and photopatch tests with various cosmetics, coal tar dyes, perfumes, lanolin preparations and parabens-mix were performed in 53 patients with pigmented cosmetic dermatitis similar in clinical appearance to Riehl's melanosis. The results showed that coal tar dyes, particularly brilliant lake red R, were closely related to the cause of the disease. In patch testing and photopatch testing with coal tar dyes, the incidence of positive responses to the brilliant lake red R was found to be significantly higher than that to the other coal tar colors (22/38 = 57.9%). The relevance of ultraviolet light to the disease was found to be much less than the ratio expected (14/47 = 29.8%). A high incidence of positive responses to fragrances was also found, but it is considered to play a secondary role in the etiology of the disease.