Corticosteroid contact allergy is not uncommon. The diagnosis can be made with either patch testing or intradermal (ID) testing. In view of a few problems that have been encountered with patch testing, patch testing is considered inferior to ID testing. The reported reproducibility of positive patch-test results in the literature ranges from 47 to 98%.
This study was conducted to (1) determine the reproducibility of patch testing with topical steroid preparations and their clinical relevance, (2) correlate positive results with ID testing, (3) address the issue of cross-reactivity between different steroid groups, and (4) identify the percentage of positive reactions to preservatives and vehicles used in commercial topical steroids.
A total of 19 patients with positive patch-test reactions to steroids from 1995 to 2004 were identified. Atopic patients and patients with type I hypersensitivity were excluded. The patients were patch-tested with a steroid series, select commercial steroid products, and vehicles and preservatives used in these preparations. The same patients were subjected to ID testing with select steroids. Readings were done on days 2, 5, and 7. ID testing was also performed on 9 control patients.
Tixocortol-21-pivalate is the most common steroid allergen (68%). The reproducibility of patch testing with topical steroid preparations ranged from 66 to 100%. Reactions to both ID testing and patch testing occurred in 16 patients (89%); 1 patient reacted to patch testing and 1 other reacted to ID testing. Formaldehyde and formaldehyde releasers accounted for the majority of reactions in the vehicles and preservatives group.
Patch testing is sufficient in diagnosing allergic contact dermatitis from topical steroids. Testing with commercial products is not a good screen for steroid allergy. The most common cross-reactions were between group A (hydrocortisone-type) corticosteroids and group D2 corticosteroids (composed of labile esters, with a long-chain ester at C17 and possibly C21).
From the Division of Dermatology, University of Ottawa, Ottawa, Ontario, Canada.
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