Contact Dermatitis — SCE Dermatology MCQ

Correct answer: A — Adhesive tapes/plasters, cosmetics, waxing products, shoe polish, and soldering flux

The correct answer is A: adhesive tapes/plasters, cosmetics, waxing products, shoe polish, and soldering flux. Colophony (rosin) is derived from pine and spruce resin, and its adhesive and tackifying properties mean it is incorporated into a very wide range of everyday and occupational products rather than being confined to a single category. Medical adhesive tapes and plasters are a classic sensitising source, and cosmetics (mascara, lipstick), depilatory waxes, shoe polish, and soldering flux are all recognised, well-documented reservoirs of colophony exposure. Because colophony is included in the baseline (standard) patch test series used in the UK, a positive reaction should prompt broad allergen avoidance advice covering all these product groups, not just one, since missing any single source risks ongoing dermatitis. This multi-source exposure pattern is precisely why colophony allergy is clinically important and why single-category options are inadequate. Why the other options are wrong: B. Only sunscreens: Colophony is not a recognised sunscreen ingredient; sunscreen allergy is more typically related to UV filters such as avobenzone or oxybenzone, so restricting the answer to sunscreens misses the actual major sources. C. Only industrial solvents: Colophony is a resin, not a solvent, and industrial solvents are not a typical colophony source; this option misrepresents the chemistry and exposure route entirely. D. Only hair dyes: Hair dye allergy is driven by para-phenylenediamine (PPD) and related compounds, not colophony, so this option confuses two distinct allergen categories. E. Only rubber products: Rubber allergy is usually due to thiurams, carbamates, or rubber accelerators, not colophony; although colophony can appear in some rubber cements, restricting the answer to rubber alone omits the far more common cosmetic, adhesive, and soldering exposures. Key point: Colophony is a ubiquitous resin allergen found across adhesives, cosmetics, waxing products, shoe polish, and soldering flux, so patch-test-confirmed allergy requires broad multi-product avoidance advice, not restriction to one category.

Reference: DermNet NZ, Colophony (rosin) contact allergen, https://dermnetnz.org/topics/colophony