Myroxylon pereirae (Balsam of Peru): still worth testing?

BACKGROUND: Based on the facts that Myroxylon pereirae (MP), or Balsam of Peru, is nowadays almost not used "as such", and fragrance mix 1 (FM1) apparently is more sensitive in detecting fragrance allergy, the usefulness of testing MP in baseline series was recently questioned.OBJECTIVES: Identification of the number of clinically relevant patch test reactions to MP not detected by FM1.METHODS: Retrospective analysis of 12030 patients patch tested with MP and FM1 for contact dermatitis between January 2018 and December 2019 in 13 Italian dermatology clinics.RESULTS: 439 patients (3.6%) had positive patch test reaction to MP, 437 (3.6%) to FM1. Positive reactions to MP and FM1 were observed in 119 subjects (1.0%), 310 (2.6%) reacted to MP only, 304 (2.5%) to FM1 only, 5 to MP and sorbitan sesquioleate (SSO), 9 to FM1 and SSO, 5 to MP, FM1 and SSO. Single sensitizations were clinically relevant in 75.2% of cases for MP (62.9% current, 12.3% past) and 76.3% for FM1 (70.1% current, 6.2% past).CONCLUSIONS: Based on our results, MP appears still worth testing along with FM1 in baseline series, because it allows detection of a remarkable number of fragrance allergies, often relevant, which would be otherwise missed. This article is protected by copyright. All rights reserved.