Allergic Contact Dermatitis to EfudexTM Cream Diagnosed by ROAT

Efudex cream (5-fluorouracil, 5-FU) is a topical antimitotic chemotherapy indicated for the treatment of actinic keratoses and superficial basal cell carcinomas, but has also been used to treat other malignant and non-malignant skin lesions. Although Efudex commonly induces an irritant contact dermatitis in lesional skin at the site of application, allergic contact dermatitis (ACD) is not frequently reported. ACD is diagnosed via epicutaneous patch testing, in which standardized chemicals are applied to the skin and evaluated by a standard protocol. There are commercially available patch test kits, but these may not contain the specific components in a topical preparation in question and more comprehensive. Furthermore, more specialized patch testing my not be readily available or economically prudent. In this report, the authors present a case of ACD to Efudex cream diagnosed by repeated open application test (R.O.A.T.) and supported by limited patch testing.