28 days follow up of patch‐test reactions to p‐phenylenediamine and p‐phenylenediamine dihydrochloride: a multicenter study on behalf of EECDRG

Background

It is discussed if routinely patch testing p‐phenylenediamine (PPD) 1.0 % petrolatum is safe due to the risk of patch test sensitization. Late appearing patch test reactions may reflect patch test sensitization, but may also be due to a low degree of pre‐existing sensitization.

Objectives

The aim of this study was to follow the positive patch test reactions to PPD and its salt PPD‐dihydrochloride (PPD‐DHC) 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. Seven follow‐up visits during 28 days followed.

Results

Twenty‐six volunteers completed the study of which 23/26 (88%) reacted to PPD 1.0%, whereas 69% reacted to 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, neither of PPD nor of PPD‐DHC.

Conclusion

No late appearing reactions were observed to PPD or PPD‐DHC at any dose. There is a risk of missing contact allergy when the dose was decreased.

This article is protected by copyright. All rights reserved.

from #Head and Neck by Sfakianakis via simeraentaxei on Inoreader http://bit.ly/2RSt7Jw