Sensitivity to petrolatum

A 30-year-old man presented with psoriasis of the scalp, elbows and sacral region. Treatment with salicylic acid (3 % in petrolatum) provoked an immediate eczematous and exudative reaction at all the treated sites, most evident on the scalp. With copper and zinc sulphate lotion, ichthyol (3 %) in calamine lotion and intravenous antihistamines, the superimposed eczema disappeared. Further application of salicylic acid (3 % in petrolatum) produced the same reaction. Suspecting some kind of topical sensitization, we patch tested the patient with standard allergens of our department. Surprisingly, the patient showed positive reactions to all the tests, with the exception of turpentine, Bisphenol A and creosote, the vehicle for which is lanette wax; for the other allergens the vehicle was yellow soft paraffin (petrolatum). Fresh patch tests with pure white soft paraffin (Lab.Cusi) and with pure yellow soft paraffin (GEHECO) showed strong positive reactions to both.