Formaldehyde allergy with initially negative open application test: a case report

Abstract

A 32-year-old housewife was referred with a 2-year history of recurrent dermatitis on the extremities and buttocks. The patch test revealed formaldehyde hypersensitivity. A 7-day repeated open application test(ROAT) to her lotion which contained DMDM hydantoin(formaldehyde donor) was negative in the antecubital fossa. When she applied it on eczematous skin, however, she felt an itching and stinging sensation. But when she applied a new lotion (no formaldehyde or formaldehyde donor) on eczematous skin it felt normal. Dermatologists often recommend moisturizers on eczematous skin. We usually ask patients to perform ROAT on normal skin only. We may need to recommend them do it on eczematous skin as well.