Scalp involvement in patients referred for patch testing: Retrospective cross-sectional analysis of North American Contact Dermatitis Group data, 1996 to 2016
4.8% of patients (2331/48,753) had scalp identified as 1 of up to 3 affected anatomic sites. Approximately one-third of "scalp-only" individuals had a specific primary diagnosis of allergic contact dermatitis. The top 3 specifically identified allergens were hair dyes, shampoo/conditioners, and consumer items (eg, hair appliances, glasses) 3. p-Phenylenediamine was the most common allergen. Isolated scalp involvement was less likely to be associated with allergic contact dermatitis
