Microscopic examination revealed a mononuclear perivascular infiltrate in the upper dermis and mild spongiosis. Careful questioning revealed that the eruption had started the same day that the patient's brother had been playing with a drop of mercury that he kept in a small glass bottle in his bedroom. The patient never touched or played with this drop of mercury.
Patch tests to mercurials disclosed strong positive reactions to both 0.5% metallic mercury in petrolatum (+++) and ammoniated mercury (+++). Negative results were observed after patch testing with 0.1% thimerosal and phenylmercury.
A Generalized Itchy Flexural Eruption in a 7-Year-Old Boy. Arch Dermatol. 2000;136(8):1055-1060. doi: