A 39‐year‐old woman presented to our emergency department for evaluation of facial and scalp rashes. The symptom onset began several weeks ago after she applied a permanent hair‐dying product. Examination of the skin revealed a primary macular rash with scattered crusted papules, superficial ulcerations, and bland erythema distributed in the periorbital tissues, hairline, scalp, ears, neck, and upper chest (Figure 1). Areas of alopecia had formed as well. Pertinent laboratory values included a white blood cell (WBC) count of 6.5 Kg/mm3 with 1.2 Kg/mm3 eosinophils.
FIGURE 1
Characteristics and distribution of the rash
Characteristics and distribution of the rash
DIAGNOSIS: ALLERGIC CONTACT DERMATITIS
Hair dyes are well recognized to cause a spectrum of allergic contact dermatitis. Hair dye products contain a veritable cornucopia of organic and inorganic compounds, and identifying the culprit agent can be challenging. The most commonly implicated agent is p‐Phenylenediamine (PPD), an aromatic amine used in henna tattoos and hair dyes. It is particularly prevalent in permanent hair dyes and darker shades. Exposure results in a type IV (delayed) hypersensitivity reaction and generally has a latency of hours to days before producing symptoms.
PPD has the dubious honor of being named the “Contact Allergen of the Year” by the American Contact Dermatitis Society.
Patch testing is considered the diagnostic gold standard. Treatment consists of removing the offending agent, and corticosteroids and antihistamines can be used as adjuncts for symptomatic management.
The dermatology literature has extensively documented this phenomenon, but it is an important entity for emergency physicians to recognize as well and should prompt questions about the usage of hair care products that may contain PPD.
FIGURE 1