A man has developed this red, linear, itchy rash where the elastic of his underwear contacts his skin. It only started after he began bleaching his underwear.
A man has developed this red, linear, itchy rash where the elastic of his underwear contacts his skin. It only started after he began bleaching his underwear.
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.
Ingestion of the offending agent can cause a diffuse cutaneous hypersensitivity reaction.
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 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. Of note, allergic contact dermatitis can be improved or cleared in some patients with dupilumab.
Allergic contact dermatitis to paraben in a hand cleanser.
Lip cheilitis secondary to ACD to a lipstick.
ACD to nickel in the glass frame.
We never found out what was the allergen in this case. But the sharp angular demarcation was clear evidence of an allergic contact dermatitis. We suspected he rested his arm on something with the allergen.
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