Patch, prick or intradermal tests to detect delayed hypersensitivity to corticosteroids?

BACKGROUND

Contact allergy to topical corticosteroids is usually detected by patch testing.

OBJECTIVES

This study compares the test results obtained with patch, prick and intradermal testing, to assess the most sensitive method for diagnosing corticosteroid hypersensitivity.

PATIENTS/

METHODS

Nineteen corticosteroid-allergic subjects and three control subjects were included. Patch, prick and intradermal tests were performed with five commercial corticosteroid preparations, as well as with the respective active principles diluted in ethanol. The test readings were performed at different time points, i.e. at 8, 24, 48 and 96 hr, and at 7 days.

RESULTS

Patch tests with ethanolic preparations produced more positive reactions than the commercial ones. The intradermal tests became positive earlier than the patch tests, a concordance between patch and intradermal tests being found in 11/15 (two positive intradermal test results with negative patch test results and vice versa). However, several subjects developed skin atrophy (14/22) at intradermal injection sites.

CONCLUSION

Patch testing with the active principles diluted in ethanol remains the diagnostic method of choice for the detection of delayed hypersensitivity to corticosteroids. Intradermal tests with late readings, despite detecting additional contact allergy cases, should not be routinely performed, because of an important risk of atrophy, particularly with corticosteroid suspensions.