By Gary M. White, MD
Allergic contact dermatitis to the paraben in a hand cleanser.
Allergic contact dermatitis (ACD) is the cell-mediated immune reaction to an allergen that has come in contact with the skin.
An eczematous, red, scaly, itchy rash develops at the site of skin contact with the allergen. Vesicles and bulla may form. Oozing of fluid is common in severe cases. Occasionally, men may transfer the allergen to the penis, causing significant swelling.
The history is critical. Exposure to the allergen with direct contact to the skin days or even a week before onset of the rash is typical. Patch testing (PT) is confirmatory.
Of course, avoidance of the allergen is key. A strong topical steroid, e.g., clobetasol, is in order. For diffuse cases, a course of oral corticosteroids, e.g., prednisone 1 mg/kg/day initially and tapered over 10-14 days, may be needed. Tapering too soon results in a flare.
For chronic cases, where the cause is unknown, patch testing is invaluable.
If patch testing is difficult or impractical, one option is preemptive avoidance in which the patient avoids the top 10 allergens for their demographic. For example, for children, the top ten allergens are neomycin, balsam of Peru, fragrance mix, lanolin, cocamidopropyl betaine, formaldehyde, corticosteroids, methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI), propylene glycol, and benzalkonium chloride. The authors of this article [Expert Review of Clinical Immunology 2016;12] estimate that one third of children suffering from ACD could potentially benefit from a "pre-emptive avoidance strategy" (P.E.A.S.).
This young girl picked flowers the day before.
ACD to a topical product causing acute facial swelling and edema.
Allergic contact dermatitis to nickel.
Allergic contact dermatitis to lipstick.
Allergic contact dermatitis to bleached elastic.
Allergic contact dermatitis to hair dye (paraphenylenediamine).
Note the angulated nature of the border of the bulla.
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