Contact dermatitis
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We report the first case of immediate-type hypersensitivity caused by Emla cream. A 55-year-old woman, after using Emla cream, went on to develop urticaria. An open test was positive to Emla cream. ⋯ An intradermal test and subcutaneous administration of 3 anaesthetics that had negative patch tests and prick tests were performed and well tolerated, allowing their use. In the literature, anaphylactic reactions to lidocaine injections, delayed-type hypersensitivity after lidocaine subcutaneous injections and contact dermatitis from Emla cream have all been described. This first case of contact urticaria from Emla cream was due to lidocaine and did not show any cross-reaction with other local anaesthetics.
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The allergens causing mango dermatitis have long been suspected to be alk(en)yl catechols and/or alk(en)yl resorcinols on the basis of observed cross-sensitivity reactions to mango in patients known to be sensitive to poison ivy and oak (Toxicodendron spp.). Earlier, we reported the 3 resorcinol derivatives: heptadecadienylresorcinol (I), heptadecenylresorcinol (II) and pentadecylresorcinol (III); collectively named 'mangol', as mango allergens. In this study, we extracted the 1st 2 components (I and II) from the Philippine mango, adjusted them to 0.05% concentration in petrolatum and patch tested the components on 2 subjects with mango dermatitis. ⋯ To investigate the cross-reaction between mangol and urushiol, we also patch tested the same subjects with urushiol. The subject sensitive to II reacted to urushiol. 6 subjects with a history of lacquer contact dermatitis and positive reactions to urushiol were similarly patch tested. 5 persons reacted to I. 2 subjects also exhibited a slower but positive reaction to II. This is the 1st report in which heptadec(adi)enyl resorcinols known to be present in mango have been shown to elicit positive patch test reactions in mango-sensitive patients.