Updating the British Society for Cutaneous Allergy Facial Series to ensure accurate diagnosis of allergic contact dermatitis

Allergic contact dermatitis (ACD) is a localised form of dermatitis or eczema which occurs 48‐72 hours after a substance which causes allergy (an allergen) has been in contact with the skin. It affects 20% of people. ACD to cosmetics is widely reported, with facial eczema being the main presenting complaint. ACD to cosmetics is diagnosed by patch testing to the British Society of Cutaneous Allergy (BSCA) facial series. Patch testing is a specialist test performed by a dermatologist which involves applying a series of allergens to the patient’s back, which remains in place for 48 hours until they are removed. The patient then returns, 72 hours after the initial application of the allergens, for the final readings to see if they have any positive allergic reactions. To ensure we are accurately diagnosing ACD, patch test series should be continually reviewed to identify relevant and emerging allergens and remove those that are outdated. The BSCA facial series currently recommends 26 allergens and was last modified in 2012. We set out to update the BSCA facial series. We assessed the results from 12 U.K. and Ireland patch test centres’, facial series from January 2016 to December 2017. We recorded the number of allergens tested in each centre and calculated the patch test rate for each allergen, using a 0.3% positive patch test rate as the threshold criterion for inclusion. A total of 4224 patients were patch tested to the BSCA facial series. The number of allergens included in individual centres facial series ranged from 24 to 66 with a total of 103 allergens tested across all centres. Twelve of the 26 allergens in the BSCA facial series had a positive patch test rate of less than 0.3% and 14 had a rate more than 0.3%. Twenty‐five allergens not recommended in the BSCA facial series had a positive patch test rate more than 0.3%. Despite a recommended facial series, there is wide variation in practice amongst patch test centres. Using our results, we have updated the BSCA facial series which now contains 24 allergens. Fifteen allergens remain, 11 allergens have been dropped and nine new allergens have been added. Linked Article:   Rolls et al. Br J Dermatol 2021; 184 :151–155.