Contact allergy to balsam of Peru. II. Patch test results in 102 patients with selected balsam of Peru constituents

Abstract

Background: In Switzerland, Germany, and Austria, allergic reactions to balsam of Peru (BP) have now made it the third most common contact allergen. Objective: A series of 20 single BP constituents (including resorcinol monobenzoate), established in 1995, was used for patch tests in patients with a positive reaction to BP in the standard series. Materials and Methods: Between 1995 and 1998, 2,273 patients were tested with the standard series, including BP, fragrance mix (FM), and propolis. Patients positive for BP were requested to participate in a further test using the 19 compounds of the BP constituents and resorcin monobenzoate (BP series); 102 patients agreed and were patch tested. The results of the 72-hour reading were used for the evaluation. Results: A total of 93 patients reacted to 1 or more of the BP series compounds. Positive reactions were seen, in decreasing order, to cinnamic alcohol, cinnamic acid, coniferyl benzoate, benzoic acid, cinnamyl cinnamate, eugenol, resorcinol monobenzoate, coniferyl alcohol, and benzyl alcohol. There were no positive reactions to vanillin or ferulic acid. A correlation between skin lesions and frequent consumption of sweets was found in 7 patients with major positive test reactions to coniferyl benzoate and benzyl alcohol. Most of the reactions to eugenol and isoeugenol had less to do with BP itself than with a primary sensitization to fragrances. Although resorcin monobenzoate (RMB) has up to now not been detected in BP, 16 patients reacted distinctly to this compound. Eleven were strong smokers; the remaining ones had contact with plastic materials that have been reported to contain RMB. RMB is used frequently as an antioxidant in synthetic material. When these patients stopped smoking, the skin lesions cleared. However, consumption of sweets caused recurrences. Conclusion: The evaluation of reactions to single constituents of BP by testing with the special BP series facilitates understanding how sensitization may be acquired. The allergen may prove to be BP itself or 1 or more of its constituents. Testing for the constituents of this series may provide patients with a more specific allergen diagnosis and may facilitate improved therapy. BP may function as an important indicator for contact allergy to RMB.