Pigmented contact dermatitis.

Pigmented contact dermatitis (PCD) is a noneczematous variant of contact dermatitis, characterized clinically by hyperpigmentation with little or no signs of dermatitis. The term “pigmented contact dermatitis” was coined by Osmundsen, a Danish dermatologist who described an epidemic of melanosis in Copenhagen.[1] In a series of excellent observations and investigations, he proved that the melanosis was in fact due to contact dermatitis caused by an “optical whitener” present in a washing powder. The chemical responsible was shown to be a mixture of two “pyrazoline” derivatives that seem to have a marked tendency to induce pigmented contact dermatitis. Many chemicals with a similar tendency have been identified in the subsequent years. Consequently, a great deal of knowledge has been acquired in the field of pigmented contact dermatitis.