Premium
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
Author(s) -
Young Ewa,
Andersen Klaus E.,
Bruze Magnus,
GiménezArnau Ana,
RossHansen Katrine,
Johansen Jeanne D.,
Madsen Jakob Torp,
Zimerson Erik,
Svedman Cecilia
Publication year - 2019
Publication title -
contact dermatitis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 96
eISSN - 1600-0536
pISSN - 0105-1873
DOI - 10.1111/cod.13235
Subject(s) - patch test , medicine , sensitization , p phenylenediamine , allergy , allergic contact dermatitis , contact dermatitis , dermatology , contact allergy , patch testing , skin test , immunology , tuberculosis , chemistry , pathology , organic chemistry
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.