CD11 Techniques for patch testing interpretation in patients with skin of colour: a systematic review of the literature and textbooks

• Published in: British journal of dermatology (1951) 2024-06, Vol.191 (Supplement_1), p.i92-i93
• Main Authors: Selvendran, Subothini Sara, Goldsmith, Portia
• Format: Article
• Language: English
• ISSN: 0007-0963; 1365-2133
• DOI: 10.1093/bjd/ljae090.190

By 2031, approximately 15% of the UK population will comprise individuals with skin of colour. Allergic contact dermatitis can result in significant morbidity, and patch testing is the gold standard to detect triggers. Under-representation of those with skin of colour in educational materials may contribute to false negative patch testing and underdiagnosis of contact dermatitis in this population. Our aim was to investigate the extent to which images of positive patch tests in individuals with skin of colour are represented in the literature. A systematic search of the PubMed database and the Royal Society of Medicine (RSM) electronic library from conception to date was conducted. This revealed 903 articles and 2034 resources, respectively. Screening titles and abstracts revealed that six articles on PubMed and one paragraph in an electronic book on the RSM database commented on patch testing in those with skin of colour. Of these, only one article on PubMed included images of positive patch test results in individuals with skin of colour. In our department, 60% of patients have skin of colour. We describe our techniques for patch test readings and present an example of how positive reactions can be missed. We recommend using a tangential light at a 45° to 90° angle to reveal any areas of skin that are papular. The skin under all the areas where patches have been applied should be gently palpated by running an index finger over the skin to assess whether they are raised or infiltrated. A 61-year-old Afro-Caribbean woman underwent patch testing. Positive patch test reactions to fragrance mix I, fragrance mix II, geraniol, citral, limonene and thiuram were observed. These were demonstrated through a cluster of vesicles and papules that were skin coloured rather than erythematous. The use of tangential lighting enabled visualization of the results and mitigated glare. In summary, our literature review has shown that there is an omission in textbooks and papers on the challenges of how to read patch tests in patients with skin of colour. There is a need to increase the awareness of the pitfalls of looking for skin erythema and how to use simple techniques such as tangential lighting and palpation to help detect positive patch test reactions. This information coupled with images should be in educational materials to prevent underdiagnosing contact dermatitis and healthcare inequalities for people with skin of colour.