The main objective of this study is to determine the efficiency of the photodynamic therapy in the treatment of epidermic dysplasies for patients affected by dystrophic epidermolysis bullosa (DEB). The secondary objectives are to evaluate the tolerance of this treatment in terms of pain and healing, and to evaluate the contribution of confocal microscopy in the diagnosis of epidermal dysplasia for patients affected by hereditary dystrophic epidermolysis bullosa. The main evaluation criterion is the cutaneous biopsy before and after (M2) a PDT session of an epidermal dysplasia area. The secondary criteria are the evaluation of the pain during the PDT session and the healing of the cutaneous lesion at M0, M2 and M4 (lesion area and healing time) and correlation histology / MC. Each patient with a suspicious lesion will be biopsied. In case of agreement for this protocol, there will be 1 PDT session followed by a consultation of control at 2 and 4 months after the end of treatment.