[Photodynamic therapy in dermatology, a new therapeutic tool]

Photodynamic therapy is a treatment aimed at to destroy pathological tissues. The therapeutical effect is obtained by the joint action of a photosensitizer and exposure to a mono or polychromatic light. The selectivity of PDT is based on the concentration of the photosensitizer in cells distinct from normal tissue due to their metabolic or proliferative state. The wave length of the excitation light is adapted to the absorption spectrum of the photosensitizer. The photochemical reaction induced by the energy of photons will produce hydroxyls radicals and oxygen singulet which will generate alterations ending up in cell necrosis or apoptosis. The main indications of PDT are the treatment of precancerous lesions and superficial skin carcinoma. Nevertheless, the therapeutical field of PDT is very large.