Squaric acid sensitization is not required for response in the treatment of alopecia areata

Abstract

Topical immunotherapy using potent contact allergens, such as squaric acid dibutylester (SADBE), can be used to treat alopecia areata. However, there are conflicting reports regarding the best protocol for its administration, particularly with regard to the necessity of an eczematous response after the initial sensitization treatment. We sought to assess the impact of initial sensitization on subsequent hair regrowth. This is a retrospective review of the use of SADBE in the treatment of alopecia areata in 14 patients. Eleven of 14 patients underwent initial sensitization before initiating treatment. Three of these patients had an eczematous reaction after 1 attempt, 5 after ≥2 attempts, and 3 failed to develop a clinical reaction. Four of 14 initiated treatment without a clinical reaction or a previous sensitization. Eleven of 14 patients experienced regrowth, 7 with previous sensitization and 4 without. This observational study is limited by sample size. SADBE sensitization regimens and reactions vary widely, and the absence of an initialeczematous reaction to sensitization does not predict a failed response with continued SADBE treatment.