Contact leukoderma caused by patch testing with dental acrylics.

Several chemicals are capable of inducing contact leukoderma. Here we report on a dental nurse who had been investigated elsewhere at a dermatology clinic 2.8 years earlier because of suspected occupational fingertip dermatitis. She had been patch tested on her upper arm with dental acrylic resins "as is." These strong concentrations of patch test substances caused a severe allergic reaction in the upper arm, and the patch test sites have remained vitiliginous for 2.8 years. Active sensitization did not take place because the patient had been sensitized earlier as shown by the allergic 2-day readings with acrylics during the first patch test session. It is assumed that acrylates induced contact vitiligo, but the dental acrylics may have also contained other chemicals (eg, hydroquinone or phenolic substances) capable of causing vitiligo. The main point to be learned from the present results is that dental acrylics should never be patch tested "as is." We also discourage the practice of use tests, open tests, or repeated open patch tests with undiluted dental acrylics because of the risk of active sensitization from single exposure.