Sorbitan sesquioleate: a rare contact allergen that is also an important indicator of allergic contact dermatitis from crossreacting compounds as well as for false-positive fragrance allergy

Abstract

Background Controversy exists about the addition of sorbitan sesquioleate (SSO) to the European baseline series for concomitant patch testing, particularly with fragrance mix (FM) I and Myroxylone pereirae (MP), which both contain SSO as an emulsifier. Aim To investigate SSO contact sensitization and concomitant positive patch test reactions to FM I or MP in Turkey. Methods This was a retrospective analysis of 840 patients consecutively patch tested with SSO 20% petrolatum between 1996 and 2020. Results The prevalence of SSO sensitization was 0.6% (5 of 840). In four of the five patients, clinical relevance could be established from SSO crossreactants, mainly in moisturizers and topical pharmaceuticals other than corticosteroids. Positive patch test reactions with unknown clinical relevance were observed to FM I or MP (both containing 5% SSO) in 71.4% of patients with a positive/questionable positive reaction to SSO (P < 0.001) and to other patch test allergens containing 1-5% SSO. Conclusions SSO was a very good indicator for positive patch test reaction with unknown clinical relevance to fragrances and other allergens containing 1-5% SSO. We suggest that SSO should be tested as a negative control with any commercially available patch test allergen containing SSO at any concentration. Moreover, clinicians should be alert for SSO synonyms and for other sorbitan derivatives in product labels, as SSO itself might not be the culprit but an indicator for crossreacting allergens.