In 1953, Lobitz and Campbell1 described an unusual, paradoxical reaction to the intradermal injection of acetylcholine and its derivative methacholine (Mecholyl) in patients with atopic dermatitis. Instead of the usual erythematous wheal and flare, a delayed blanch occurred within the flare 3 to 5 min. after injection and persisted for 15 to 30 min. The delayed blanch, which these authors attributed to vasoconstriction, spread beyond the wheal in the form of pseudopods. The occurrence of the delayed-blanch phenomenon has since been confirmed by many investigators.2-5 The general consensus is that the delayed-blanch reaction is specific for patients with atopic dermatitis, and occurs in about 70% of such patients.
The present study was undertaken to determine whether the delayed blanch is present in atopic individuals who have never had dermatitis, that is, in patients with hay fever, asthma, or both, but without any past history or present evidence of
WEST JR, JOHNSON LA, WINKELMANN RK. Delayed-Blanch Phenomenon in Atopic Individuals Without Dermatitis. Arch Dermatol. 1962;85(2):227–228. doi:10.1001/archderm.1962.01590020067007
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