Pigmented cosmetic dermatitis and coal tar dyes.

Area of Science:

• Dermatology
• Toxicology

Background:

• Pigmented cosmetic dermatitis, clinically similar to Riehl's melanosis, affects patients using various personal care products.
• Identifying causative agents is crucial for effective treatment and prevention.

Purpose of the Study:

• To investigate the role of specific cosmetic ingredients, including coal tar dyes and fragrances, in causing pigmented cosmetic dermatitis.
• To evaluate the contribution of ultraviolet light in the pathogenesis of this condition.

Main Methods:

• Patch testing and photopatch testing were conducted on 53 patients diagnosed with pigmented cosmetic dermatitis.
• Testing involved a range of substances: cosmetics, coal tar dyes (including brilliant lake red R), perfumes, lanolin preparations, and parabens-mix.
• Patients' responses to patch and photopatch tests were meticulously recorded.

Main Results:

• Coal tar dyes, particularly brilliant lake red R, showed a high incidence of positive reactions (57.9%) in patch and photopatch tests.
• Fragrances also elicited a significant number of positive responses, suggesting a secondary etiological role.
• The relevance of ultraviolet light was found to be less significant than anticipated (29.8% positive responses).

Conclusions:

• Coal tar dyes, especially brilliant lake red R, are strongly implicated as the primary causative agents in pigmented cosmetic dermatitis resembling Riehl's melanosis.
• Fragrances contribute to the condition but appear to play a secondary role.
• Ultraviolet light's role in the development of this dermatitis is less pronounced than other factors.