Sorbitan sesquioleate; a rare cause of contact allergy in consecutively patch tested dermatitis patients

Background. Sorbitan sesquioleate (SSO) has been added to fragrance mix I (FM I) as an emulsifier since the 1990s. Being a contact allergen itself, SSO has the potential to cause false-positive reactions to FM I. Recent results obtained with selected FM I-positive patients have shown that 5% have concomitant positive reactions to SSO. Objectives. To investigate the 5-year prevalence of contact allergy to SSO and evaluate the importance of SSO allergy when patch test results for FM I are interpreted. Methods. This was a retrospective database study of consecutively patch tested eczema patients (n=4 637) from 2010 to 2014. All patients were tested with our baseline series including FM I and SSO 20% in pet. Results. Sensitization to SSO was identified in 9 (0.2%) patients. The proportion of FM I-positive patients with concomitant positive reactions to SSO was 1.4%. Conclusions. SSO is a rare cause of contact allergy, with a 5-year prevalence of 0.2% in consecutively tested patients. Contact allergy to the emulsifier does not play a major role when the overall frequency of contact allergy to FM I is evaluated. However, to correctly diagnose individual patients, concomitant patch testing with FMI and SSO is encouraged.