Patch-test readings after day 5 have previously been used to identify delayed reactions to metals and topical antibiotics.
The aims of this study were to identify allergens for which late readings (beyond day 5) would be most valuable and to compare our results with our previous study on delayed patch-test readings.
This was a retrospective study of 298 patients who underwent metal and corticosteroid series patch testing from January 1, 2007, through December 31, 2013. Patch-test readings were conducted on days 3 and 5 and at least once sometime between days 7 and 14. All reactions were examined at each reading.
These results were concordant with our previous findings that additional readings after day 7 are particularly useful for identifying reactions to metals (gold, cobalt, beryllium, palladium), specific preservatives (dodecyl gallate, propolis), and the topical antibiotic neomycin. New delayed reactions to bacitracin, p-phenylenediamine, and topical corticosteroids were not seen in this cohort.
From the *Mayo Clinic School of Medicine, Mayo Clinic College of Medicine and Science; and †Division of Clinical Dermatology, Mayo Clinic, Rochester, MN; ‡Department of Dermatology, Mayo Clinic, Jacksonville, FL; §Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN; and ∥Division of Clinical Dermatology, Mayo Clinic, Scottsdale, AZ.
Address reprint requests to Mark D. P. Davis, MD, Division of Clinical Dermatology, Mayo Clinic, 200 First St SW, Rochester, MN 55905. E-mail: firstname.lastname@example.org.
The authors have no funding or conflicts of interest to declare.