Atypical or Severe Contact Eczema from Cinnamon Essential Oil

The document discusses three cases of atypical or severe contact eczema related to different substances. The first case describes a 40-year-old woman with a history of atopy who was hospitalized due to a severe generalized eczematous eruption caused by an allergy to methylisothiazolinone (MI), a preservative found in many cosmetic, household, and professional products. Patch testing confirmed the allergy, and avoiding the allergen led to remission. This case emphasizes the need for systematic testing for MI in cases of unexplained generalized eczema and suggests considering the inclusion of MI testing in the standard European battery of tests. The second case involves four patients without a history of eczema who developed skin lesions after exposure to essential oils, particularly cinnamon oil, over a period of 3 to 52 weeks. Patch tests confirmed an allergy to cinnamon oil, specifically to cinnamaldehyde, which was the main allergen. The document highlights the severity of the clinical presentations and the variety of exposure sources, including pharmaceutical, professional, and cosmetic. It concludes that cinnamon essential oil can cause atypical or severe contact reactions and that cinnamaldehyde was the responsible allergen in these cases, with no cross-reactions observed with other essential oils tested. The third case is not detailed in the summary provided, but it appears to relate to occupational dermatitis caused by proteins from seafood, questioning whether fishermen or cooks are more affected. The study aimed to identify the prevalence of contact dermatitis among these professions by examining cases from the National Network for the Surveillance and Prevention of Occupational Diseases (RNVPPP) using the ICD-10 code for allergic contact dermatitis where the allergen was fish, crustaceans, mollusks, or algae.