Occupational allergic contact dermatitis from methyl aminolevulinate

Photodynamic therapy (PDT) is used to treat certain types of nonmelanoma skin cancer. Metvix cream applied topically in PDT is composed of the active substance methyl aminolevulinate and 14 excipients composing the vehicle. One case of occupational allergic contact dermatitis from methyl aminolevulinate is reported. A 49-year-old nurse's aide working in a PDT unit in the dermatology department developed a dermatitis involving the eyelids and fingers. The lesions began a few months after she started working in that unit. Patch tests were performed with the standard series (Spanish Group for Research into Dermatitis and Skin Allergies [GEIDAC]), cosmetics series, Metvix cream "as is," the Metvix vehicle supplied by the manufacturer, and some of the excipients separately (methyl para-hydroxybenzoate [Nipagin M], propyl para-hydroxybenzoate [Nipasol M], isopropyl myristate, cetostearyl alcohol [Lanette N], and disodium edetate). After day-2, day-4, and day-7 readings, positive results were achieved only with Metvix cream "as is." Tests performed on a control group of 15 individuals were negative. Literature on cases of allergic contact dermatitis from methyl aminolevulinate is reviewed. It should be emphasized that the present case is the first occupational case reported so far.