The benefit of patch testing with a corticosteroid at a low concentration

image Patch testing with corticosteroid marker molecules is advocated because testing with all available corticosteroids is impossible in clinical practice. Most commonly used are budesonide, tixocortol pivalate, and hydrocortisone-17-butyrate. We have been patch testing not only with the three markers, but also with two corticosteroid mixes, each consisting of different concentrations of the three markers. image We describe a patient allergic to toxicortol pivalate, who was diagnosed by using a lower patch test concentration that recommended, 0.1% in petrolatum, as well as a weak corticosteroid mix, 0.202%. image The patient was patch tested to a standard series, including the two corticosteroid mixes and its three constituents. image None of the corticosteroid preparations were positive on the first ordinary reading day, day 3, whereas both tixocortol pivalate at 0.1% and the corticosteroid mix at 0.202% were positive on the second ordinary reading day, day 7, whereas all tested corticosteroids in the standard series gave positive reactions on d10. image The possible benefit of patch testing with a corticosteroid at a low concentration is supported, as is the significance of late readings beyond D4.