Early diagnosis of drug overdosage may be difficult in a comatose patient. This report concerns such a case. The patient's thigh was stroked with the back of the thumbnail and dermographism developed within four minutes. This was followed by an erythematous line and vesicles that lasted for six days. Three days after stroking, microscopic sections of the lesion revealed subepidermal vesicles and necrosis of sweat glands.
Leavell UW, Coyer JR, Taylor RJ. Dermographism and Erythematous Lines in Glutethimide Overdose. Arch Dermatol. 1972;106(5):724-725. doi:10.1001/archderm.1972.01620140068021