Highlighting is a very popular and common hair treatment in American society. Despite the frequency of hair highlighting activities, reports of caustic cutaneous burns resulting in blisters lasting weeks, indicative of a second degree burn (as alleged in this case), are exceedingly rare.
Hair highlighting is accomplished by decolorizing the hair melanin pigment and dying the hair strands. This involves the application of hydrogen peroxide at an alkaline pH along with specific dyes. For this process to cause a chemical burn, several hours of direct skin contact with strong alkali or other chemical would be required.
There are three possibilities in a differential diagnosis of the pathogenesis of localized scalp changes following highlighting associated with immediate subjective complaints of burning: 1) a chemical or caustic burn; 2) a delayed immunologic event in the form of allergic contact dermatitis (ACD) from an unknown chemical exposure; or, 3) some pre-existing, hypersensitizing exposure/event.
Pathogenesis of localized scalp changes following hair highlighting medical expert witness specialties include dermatology, burn medicine, and allergy.