Severe cutaneous reaction to photodynamic therapy with blue light.

Photodynamic therapy (PDT) has been considered a safe and efficacious treatment for actinic keratoses (AKs) of the scalp and face. The procedure involves exposing a patient to a blue light source 1-4 hours after application of photosensitizing aminolevulinic acid (ALA) at a dose of 10 J/cm2 for up to 1000 seconds.(1,2) We suggest that amount of exposure time and area of exposure should be stratified according to baseline photodamage.