Background: Contact allergy to grease is rare and often not even suspected. We investigated such a case in which the detected allergen was the stabilizer in the grease, which is rarely found as an allergen.
Objective: Thin-layer chromatography (TLC) was used in a novel way and helped detect the allergen.
Methods: Patch testing with our standard series, a metal-working series, the different substances individually, the grease in serial dilution and extracts of personal objects, the TLC plate. Gas chromatography-mass spectrometry was also used.
Results: Test results indicated contact allergy to grease containing N-phenyl-1-naphthylamine and contact allergy to Disperse Orange 1, N-cyclohexyl-N'-phenyl-4-phenylenediamine, N-isopropyl-N'-phenyl-4-phenylenediamine, and N,N'-diphenyl-4-phenylenediamine.
Conclusion: N-phenyl-1-naphthylamine was the main cause of the patient's dermatitis. This case report underlines the importance of testing the patient's own products and also underlines the benefit of using TLC strips for patch testing and of visiting the workplace to get correct information about exposure conditions.