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

Abstract

Background: There is an ongoing discussion on whether routinely patch testing with pphenylenediamine (PPD) 1.0% pet. is safe, owing to the risk of patch test sensitization. Lateappearing 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 PPDsensitized 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.active sensitization, allergic contact dermatitis, contact allergy, delayed, dilution series, falsenegative reactions, hypersensitivity, late-appearing patch test reactions, PPD

Value of photo assessment in late patch test readings—A multicenter study from six European patch test clinics

“…The number of delayed reactions is anticipated to be associated with some uncertainty, since photos were submitted from 65.3% of the patients only, and a clinical examination was not performed to confirm the reactions, for which reason we cannot preclude that some reactions may have been missed. However, the magnitude of the problem regarding delayed reactions seems to be quite small and not correlated to one or more specific allergens 31‐33 …”

Beard dermatitis induced by coloration

“…The issue of active sensitization by patch testing is discussed controversially, with some countries not including PPD 1% pet. in their baseline series or reducing the 1% recommended concentration, albeit with a risk of missing allergies . The diagnostic workup of ACD to coloring cosmetics requires a series of dyes including PPD and other aromatic amine‐based dyes for diagnosis and alternative proposals, but frequent cross‐sensitization results in multiple positive patch test reactions .…”

Kontaktallergien – Neu aufkommende Allergene und Auswirkungen für das Gesundheitswesen

“…Bisweilen ist hiervon nicht die Person, die das Haarfärbemittel verwendet, selbst betroffen, sondern ihr (Tanz-)Partner; dies wird als Partner- oder Consort-Dermatitis bezeichnet [261, 262]. Neben den häufigen Sensibilisatoren wie p-Phenylendiamin (PPD) [263] und Toluol-2,5-Diamin wird gelegentlich auch über „seltene“ Ursachen z. B. durch verschiedene Kupplerkomponenten berichtet, z.…”