Twenty-eight-day follow-up of patch test reactions to p-phenylenediamine and p-phenylenediamine dihydrochloride: A multicentre study on behalf of the European Environmental and Contact Dermatitis Research Group

Ewa Young, Klaus E. Andersen, Magnus Bruze, Ana Giménez-Arnau, Katrine Ross-Hansen, Jeanne D. Johansen, Jakob Torp Madsen, Erik Zimerson, Cecilia Svedman

    Research output: Contribution to journalArticleResearch

    3 Citations (Scopus)

    Abstract

    © 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Background: There is an ongoing discussion on whether routinely patch testing with p-phenylenediamine (PPD) 1.0% pet. is safe, owing to the risk of patch test sensitization. Late-appearing patch test reactions may reflect patch test sensitization, but may also be attributable to a low degree of pre-existing sensitization. Objectives: To follow the positive patch test reactions to PPD and its salt PPD dihydrochloride (PPD-DHC) in order to characterize reaction patterns concerning time and dose in PPD-sensitized individuals. Methods: Volunteers with previous reactions to PPD 1.0% were included and patch tested with PPD and PPD-DHC in equimolar dilution series. There were then seven follow-up visits over a period of 28 days. Results: Twenty-six volunteers completed the study, of whom 23 of 26 (88%) reacted to PPD 1.0%, and 69% reacted to PPD 0.32%. Altogether, 42% and 27% reacted to the corresponding equimolar concentrations of PPD-DHC. After day 7, no new reactions were observed to any concentration tested, either of PPD or of PPD-DHC. Conclusion: No late-appearing reactions to PPD or PPD-DHC were observed at any dose. There is a risk of missing contact allergy when the dose is decreased.
    Original languageEnglish
    Pages (from-to)1-8
    JournalContact Dermatitis
    Volume81
    DOIs
    Publication statusPublished - 1 Jul 2019

    Keywords

    • active sensitization
    • allergic contact dermatitis
    • contact allergy
    • delayed
    • dilution series
    • false-negative reactions
    • hypersensitivity
    • late-appearing patch test reactions
    • PPD

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