Compositae mix is a more sensitive test for Compositae dermatitis than the sesquiterpene lactone mix

Abstract

Over the past 2 decades, Compositae dermatitis has increasingly been recognized as a cause of exposure-pattern dermatitis. The introduction of the sesquiterpene lactone (SL) mix as a screening test has contributed to this improved recognition. However, there is growing evidence that the SL mix fails to detect a substantial number of genuine Compositae allergies. We therefore investigated whether another screening reagent (the Compositae mix) might be more sensitive in detecting cases of Compositae allergy than the SL mix. Over a 1-year period, we tested 656 consecutive unselected patch test patients to both SL mix and Compositae mix. 31 patients were found to have genuine Compositae allergies. Of these, 28 had reacted to the Compositae mix but only 13 had reacted to the SL mix. The Compositae mix failed to detect only 2 genuine Compositae allergies, whereas the SL mix missed 17 such allergies. On the other hand, the Compositae mix led to 9 irritant reactions, while there was only 1 irritant reaction with the SL mix. We conclude that Compositae dermatitis is still being underdiagnosed with the current screening method, and that the Compositae mix is significantly more sensitive in detecting Compositae allergy than the SL mix.