Contact Dermatitis — SCE Dermatology MCQ

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HardInflammatory DermatosesContact DermatitisSCE Dermatology

A 30-year-old woman has chronic hand eczema. She is a florist and handles chrysanthemums daily. Patch testing shows a positive reaction to Compositae mix. What is the active sensitising chemical group in Compositae plants?

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Correct answer: E — Sesquiterpene lactones

Sesquiterpene lactones (SQLs) are the primary sensitising compounds in Compositae (Asteraceae) family plants, which include chrysanthemums, daisies, sunflowers, chamomile, ragweed, lettuce, and artichokes. Florists are at particular occupational risk due to daily handling of chrysanthemums. The Compositae mix used in patch testing contains a mixture of SQLs including alantolactone, dehydrocostus lactone, and costunolide. Cross-reactivity between different Compositae species is common. Affected individuals should avoid handling Compositae plants and products containing Compositae extracts (herbal medicines, cosmetics containing chamomile or arnica). Urushiol is the allergen in poison ivy/oak (not UK-relevant).

Reference: BAD 2017 Contact Dermatitis Guidelines